JP4209591B2 - Absorber with improved distribution characteristics under subsaturation - Google Patents

Description

【０３８６】
＜装置機構の一般的説明＞
本試験のために使用する図２（Ａ）において、一般的に５２０として示されている毛管吸着試験装置は、ＴＡＰＰＩ条件（５０％ＲＨ、２５℃）下で操作される。試験サンプルは、試験液を含有する５０６として表示されているはかり付き液体リザーバに試験液（合成尿）の連続カラムを通して接続された、図２（Ａ）に５０２として示されているガラス・フリット上に載置される。このリザーバ５０６は、コンピュータ（図示されていない）に接続されたはかり５０７上に置かれる。はかりは、０．００１ｇまで読み取ることができなければならない；そうしたはかりはＰＲ１２０３としてＭｅｔｔｌｅｒ Ｔｏｌｅｄｏ（ニュージャージー州、ハイツタウン）から入手可能である。ガラス・フリット５０２は、試験サンプルを様々な吸引高さへ暴露させるために試験サンプルの垂直運動を可能にするように、概して図２（Ａ）において５０１として示されている垂直スライド上に置く。垂直スライドは、試験サンプルによる液体取り込み量を測定するために吸引高さ及び対応する時間を記録するためにコンピュータへ取り付けられるロッドレス駆動装置であってよい。好ましいロッドレス作動装置はコンピューモーター(CompuMotor)（ローナート、カリフォルニア州）から入手可能な電動装置ＺＥＴＡ６１０４−８３−１３５によって動力を供給できる製品２０２Ｘ４Ｘ３４Ｎ−１Ｄ４Ｂ−８４−Ｐ−Ｃ−Ｓ−Ｅとして、インダストリアル デバイス(Industrial Devices)（ノヴァト、カリフォルニア州）から入手できる。データが測定されて駆動装置５０１及びはかり５０７からデータが送られると、各試験サンプルについて、毛管吸着吸収容量データが容易に発生される。同様に、駆動装置５０１にコンピュータが接続されていることによって、ガラス・フリット５０２の垂直運動を制御することもできる。例えば、駆動装置は各吸引高さで「平衡」（下記で定義される）に到達した後にのみ、ガラス・フリット５０２を垂直に移動させるように指令できる。
【０３８７】
ガラス・フリット５０２の下部は、ドレーン三方活栓５０９にフリット５０５を接続するＴｙｇｏｎ（登録商標）チューブへ接続されている。ドレーン活栓５０９は、ガラス管５０４と活栓５１０によって液体リザーバ５０５へ接続されている。（活栓５０９は装置の洗浄中若しくは気泡の除去中にのみドレーンへ向かって開かれる。）ガラス管５１１は、活栓５１０によって液体リザーバ５０５とはかり付き液体リザーバ５０６とを接続する。はかり付き液体リザーバ５０６は軽量１２ｃｍ径ガラス皿５０６Ａ及びカバー５０６Ｂから構成される。カバー５０６Ｂはそれを通してガラス管５１１がリザーバ５０６内の液体に接触する穴を有する。ガラス管５１１はカバー５０６Ｂに接触してはならず、さもないと不安定なはかり読み値が生じ、試験サンプル測定値を使用できなくなる。
【０３８８】
ガラス・フリットの径は試験サンプルを保持するために下記で説明するピストン・シリンダ装置に適合するために十分な径でなければならない。ガラスフリット５０２には、加熱浴からの一定の温度管理ができるようにジャケットを付けなければならない。フリットは、♯３６０６０−３５０Ｆとしてコーニング ガラス社(Corning Glass Co.)（コーニング、ニューヨーク州）から入手できる４〜５．５μｍ細孔を有すると規定された３５０ｍｌフリットガラス製円形漏斗である。細孔はフリット表面が規定の毛管吸引高さで湿潤しているのを維持するのに十分なほど微細である（ガラス・フリットはガラス・フリットの下方では試験液の連続カラムに空気を進入させない）。
【０３８９】
上記のように、フリット５０２は三方活栓５１０の位置に依存してチューブによって液体リザーバ５０５又ははかり付き液体リザーバ５０６に接続されている。
【０３９０】
ガラス・フリット５０２には、定温浴からの水を受け入れるためにジャケットが付けられている。これは、ガラス・フリットの温度が試験手順中は８８°Ｆ（３１℃）の一定温度に維持されることを保証するであろう。図２（Ａ）に示されているように、ガラスフリット５０２には吸水ポート５０２Ａ及び放水ポート５０２Ｂが備えられており、これらは一般に５０８と示される循環加熱浴との閉鎖ループを作っている。（図２（Ａ）にはガラス製ジャケットは描出されていない。しかし、浴５０８からジャケットが付けられたガラス・フリット５０２へ導入される水は試験液には接触せず、試験液は定温浴を通して循環させられない。定温浴中の水はガラス・フリット５０２のジャケット壁を通って循環する。）
リザーバ５０６及びはかり５０７は、はかり付きリザーバからの試験液の蒸発を最小限に押さえるため、及び実験の実行中のはかりの安定性を強化するために箱の中に入れられている。概して５１２と示されているこの箱には上部と壁があり、上部にはそれを通してチューブ５１１が挿入されている穴がある。
【０３９１】
ガラス・フリット５０２は図２（Ｂ）により詳細に示されている。図２（Ｂ）は、吸水ポート５０２Ａと放水ポート５０２Ｂが示されていないガラス・フリットの断面図である。上記のように、ガラス・フリットは規定の４〜５．５μｍの細孔を有する３５０ｍｌのフリットガラス製円形漏斗である。図２（Ｂ）を参照すると、ガラス・フリット５０２は、５５０と指定されている円筒形ジャケット付き漏斗及び５６０として示されているガラス・フリットディスクを具備している。ガラス・フリット５０２はさらに、５７０として示されている試験サンプルを閉じ込め、さらに試験サンプルへの小さな封圧を提供する一般に５６５（シリンダ５６６及びピストン５６８を具備する）と示されているシリンダ／ピストン組立体を具備している。ガラス・フリット・ディスク５６０からの試験液の過度の蒸発を防止するために、５６２と示されているテフロン(Teflon)製リングがガラス・フリット・ディスク５６０の上部に置かれる。Ｔｅｆｌｏｎ（登録商標）リング５６２は厚さが０．０１２７ｃｍであり（♯８５６９Ｋ１６としてマクマスターキャル(McMasterCarr)からシート・ストックとして入手可能で、適切なサイズにカットされる）、シリンダ５６６の外側のフリット・ディスク面を被覆するのに使用され、従ってガラス・フリットからの蒸発を最小限に抑える。リングの外径及び内径は、各々７．６及び６．３ｃｍである。Ｔｅｆｌｏｎ（登録商標）リング５６２の内径はシリンダ５６６の外径より約２ｍｍ小さい。Ｖｉｔｏｎ（登録商標）Ｏリング（＃ＡＳ５６８Ａ−１５０及びＡＳ５６８Ａ−１５１としてマクマスターキャル(McMasterCarr)から入手可能）５６４が、蒸発の防止にさらにいっそう役立つように、円筒形ジャケット付き漏斗５５０の内壁とＴｅｆｌｏｎ（登録商標）リング５６２の間の間隙を密封するために、Ｔｅｆｌｏｎ（登録商標）リング５６２の上部に配置される。Ｏリングの外径が円筒形ジャケット付き漏斗５５０の内径より大きい場合は、Ｏリングの径を下記のようにして漏斗に適合するように低下させる：Ｏリングを切り開き、必要な量のＯリング材料を切り落とし、さらにＯリングが円筒径ジャケット付き漏斗５５０の内壁にその全周囲で接触するように再び張り合わす。
【０３９２】
上記のように、５６５として図２（Ｂ）に一般的に示されているシリンダ／ピストン組立体が試験サンプルを閉じ込め、試験サンプル５７０に小さな封圧を提供する。図２（Ｃ）を参照すると、組立体５６５はシリンダ５６６、５６８と指定されているカップ様Ｔｅｆｌｏｎ（登録商標）製ピストン、及び必要な場合は内側ピストン５６８に適合する１個又は複数のおもり（図示されていない）から構成される。（試験サンプルの乾燥時径に依存して０．２ｐｓｉの封圧が達成されるようにピストンと任意のおもりの結合重量を調整するために必要な場合に、任意のおもりは使用されるであろう。これについては下記で説明する。）シリンダ５６６はＬｅｘａｎ（登録商標）バー・ストックで、下記の寸法を有する：外径７．０ｃｍ、内径６．０ｃｍ及び高さ６．０ｃｍ。Ｔｅｆｌｏｎ（登録商標）ピストン５６８は下記の寸法を有する：シリンダ５６６の内径より０．０２ｃｍ小さい外径。図２（Ｄ）に示されているように、試験サンプルに接触しないピストン５６８の端部には０．２ｐｓｉ（１．４ｋｐａ）の試験サンプル封圧を達成するために必要な任意のおもり（試験サンプルの実際乾燥時径によって指令される）を受け入れるために、５．０ｃｍ径×約１．８ｃｍ深さのチャンバ５９０を提供するように穴が開けられている。言い換えると、ピストン５６８と何れかの任意おもり（図には示されていない）の総重量を試験サンプルの実際径（乾燥時）で割ったものは、０．２ｐｓｉの封圧が達成されるようでなければならない。シリンダ５６６及びピストン５６８（及び任意のおもり）は、毛管吸着吸収容量測定を実施する前に少なくとも３０分間に渡り３１℃で平衡させられる。
【０３９３】
毛管吸着実験中には、サンプル周囲での空気の不安定化を最小限に抑えるために、非界面活性剤処理若しくは混合紡糸穿孔フィルム（１４ｃｍ×１４ｃｍ）を使用し、ガラス・フリット５０２を覆う。穿孔部は、実験中にフィルムの下面上で凝縮が発生するのを防止するのに十分な大きさである。
【０３９４】
＜試験サンプルの調製＞
試験サンプルは、貯蔵吸収部材から５．４ｃｍ径円形構造を打ち抜くことによって入手できる。該部材が吸収体のコンポーネントである場合は、試験前に該製品の他のコンポーネントを取り除かなければならない。その構造（例、密度、コンポーネント材料の相対配置、構成材料の物理的特性その他）を著しく変更せずには該部材を製品の他のコンポーネントから分離できないか、又は該部材が吸収体のコンポーネントではない状況においては、試験サンプルは、その組合せが問題の部材を代表するように、該部材を構成する全材料を結合することによって調製する。試験サンプルは５．４ｃｍ径の円であり、アーチ・パンチを用いてカットする。
【０３９５】
試験サンプルの乾燥重量（毛管吸着吸収容量を計算するために下記で使用される）は、上記のように周囲条件下で調製された試験サンプルの重量である。
【０３９６】
＜実験の段取り＞
１．垂直スライド５０１に取り付けられた漏斗保持具に、清潔な乾燥したガラス・フリット５０２を置く。垂直スライドの漏斗保持具を、ガラス・フリットが０ｃｍ高さにあるように移動させる。
【０３９７】
２．上記のように、装置のコンポーネントを図２（Ａ）に示されたように据え付ける。
【０３９８】
３．１２ｃｍ径のはかり付き液体リザーバ５０６をはかり５０７上に置く。プラスチック製蓋５０６Ｂをこのはかり付き液体リザーバ５０６に被せ、はかり箱５１２にプラスチック製蓋を被せるが、それらの蓋は各々ガラス管５１１が適合して通過できるように小さい穴を具備している。ガラス管をはかり付き液体リザーバの蓋５０６Ｂに接触させてはならず、さもないと不安定なはかり読み値が生じ、測定値を使用できなくなる。
【０３９９】
４．活栓５１０をチューブ５０４に向けて閉じ、ガラス管５１１に向けて開く。はかり付き液体リザーバ５０６を充填するために試験液がチューブ５１１に流入できるように、前以て試験液が充填されている液体リザーバ５０５を開ける。
【０４００】
５．ガラス・フリット５０２を水平にし、適所に固定する。同様に、ガラス・フリットが乾燥していることを保証する。
【０４０１】
６．Ｔｙｇｏｎ（登録商標）チューブ５０３を活栓５０９に取り付ける。（チューブはキンクを伴わずに２００ｃｍの最高点でガラス・フリット５０２に到達するほど十分に長くなければならない。）Ｔｙｇｏｎ（登録商標）チューブに液体リザーバ５０５からの試験液を充填する。
【０４０２】
７．Ｔｙｇｏｎ（登録商標）チューブ５０３を水平のガラス・フリット５０２に取り付け、その後液体リザーバ５０５からガラス・フリット５０２へ導く活栓５０９及び活栓５１０を開く。（活栓５１０はガラス管５１１に対しては閉じていなければならない。）試験液をガラス・フリット５０２に充填し、水平ガラス・フリットの充填中に閉じ込められた空気全部を取り除く。液体レベルがガラス・フリット・ディスク５６０の上部を越えるまで充填し続ける。漏斗を空にし、チューブ及び漏斗の内側にあるすべての気泡を取り除く。気泡はガラス・フリット５０２を反転させ、活栓５０９のドレーンを通して気泡が立って抜け出させることによって取り除くことができる。（気泡は、典型的にはガラス・フリット・ディスク５６０の底部上に集まる。）ジャケット付き漏斗５５０の内側及びガラス・フリット・ディスク５６０の表面上に適合するであろう十分に小さいレベルを用いてフリットを再び水平にする。
【０４０３】
８．ガラス・フリットを、はかり付き液体リザーバ５０６を用いてゼロ調整する。これを行うために十分な長さの１本のＴｙｇｏｎ（登録商標）チューブを取り、それに試験液を満たす。一端をはかり付き液体リザーバ５０６内に入れ、他方の端部を使用してガラス・フリット５０２を配置する。チューブによって示される試験液のレベル（はかり付き液体リザーバのレベルと同等である）は、ガラス・フリット・ディスク５６０の上部より１０ｍｍ下方である。これが実状に合わない場合は、リザーバ内の液体量を調整するか、又は垂直スライド５０１上のゼロ位置をリセットする。
【０４０４】
９．チューブによって定温浴５０８からの放水ポート及び吸水ポートをガラス・フリットの吸水ポート及び放水ポート５０２Ａ及び５０２Ｂに各々取り付ける。ガラス・フリット・ディスク５６０の温度を３１℃にさせる。これは一部にはガラス・フリットに試験液を充填し、それが平衡温度に到達した後にその温度を測定することによって測定できる。浴からガラス・フリットへの水の移動中における熱の放散を許容するために、浴を３１℃より幾らか高い温度に設定する必要があるであろう。
【０４０５】
１０．ガラス・フリットを３０分間平衡化させる。
【０４０６】
＜毛管吸着パラメータ＞
下記では、ガラス・フリットが各高さにどの位の時間とどまっているのかを測定するコンピュータ・プログラムについて説明する。
【０４０７】
毛管吸着試験ソフトウエアプログラムでは、試験サンプルは液体のリザーバからある規定の高さにある。上記のように、コンピュータが既知の時間間隔の最後にはかりを読み取り、試験サンプルとリザーバの間の流速（デルタ読取り値／時間間隔）を計算することができるように、液体リザーバははかりの上にある。この方法の目的で、試験サンプルは、規定数の連続時間間隔に対して流速が規定流速より少ないときに平衡状態にあると見なされる。一定の材料については、規定「平衡定数」に到達したときに実際平衡には到達しない可能性があることは認識されている。読み値間の時間間隔は５秒間である。
【０４０８】
デルタ表における読み値の数は、毛管吸着メニューでは「平衡サンプル」として規定されている。デルタの最高数は５００である。流速定数は、毛管吸着メニューでは「平衡定数」として規定されている。
【０４０９】
平衡定数は０．０００１〜１００，０００の範囲内のｇ／ｓｅｃの単位で入力される。
【０４１０】
下記はロジックの簡易化された例である。表は、はかり読み値及び各時間間隔に対して計算されたデルタ流量を示している。
【０４１１】
平衡サンプル＝３
平衡定数＝．００１５
【表１】

【０４１２】
【表２】

【０４１３】
【表３】

【０４１４】
上記の簡易化された例に対する平衡取り込み量は０．３１８ｇである。
【０４１５】
下記は平衡取り込み量を決定するために使用されたＣ言語でのコードである：
【表４】

【０４１６】
＜毛管吸着パラメータ＞
負荷の説明（封圧）：０．２ｐｓｉ負荷
平衡サンプル（ｎ）：５０
平衡定数：０．０００５ｇ／ｓｅｃ
セットアップ高さ値：１００ｃｍ
最終高さ値：０ｃｍ
静水圧ヘッドパラメータ：２００，１８０，１６０，１４０，１２０，１００，９０，８０，７０，６０，５０，４５，４０，３５，３０，２５，２０，１５，１０，５及び０ｃｍ
毛管吸着試験手順は、毛管吸着吸収容量の測定のために上記に明記した全高さを上記の順序で用いて実施する。特定高さ（例、３５ｃｍ）での毛管吸着吸収容量を測定することが望ましい場合でさえ、規定された順序で静圧水ヘッドパラメータの全シリーズを完了しなければならない。試験サンプルに対する毛管吸着等温線を作成するためにはこれら全部の高さを毛管吸着試験の遂行中に使用されるが、本発明の開示では２００，１４０，１００，５０，３５及び０ｃｍの特定高さでのそれらの吸収特性に関して貯蔵吸収部材を説明する。
【０４１７】
＜毛管吸着試験手順＞
１）実験段取り手順に従う。
２）定温浴５０８のスイッチが入っており、水がガラス・フリット５０２を通って循環していること、及びガラス・フリット・ディスク５６０の温度が３１℃であることを確認する。
３）ガラス・フリット５０２を２００ｃｍの吸引高さに置く。ガラス・フリット５０２をはかり付き液体リザーバ５０６と接続するために活栓５０９及び５１０を開く（活栓５１０は液体リザーバ５０５に対しては閉じられている。）ガラス・フリット５０２は３０分間平衡化させられる。
４）上記の毛管吸着パラメータをコンピュータに入力する。
５）活栓５０９及び５１０を閉じる。
６）ガラス・フリット５０２をセットアップ高さ１００ｃｍへ移動させる。
７）Ｔｅｆｌｏｎ（登録商標）リング５６２をガラス・フリット・ディスク５６０の表面上に置く。Ｏリング５６４をＴｅｆｌｏｎ（登録商標）リング上に置く。予備加熱したシリンダ５６６をＴｅｆｌｏｎ（登録商標）リング上に同心性に置く。試験サンプル５７０をガラス・フリット・ディスク５６０上のシリンダ５６６に同心性に置く。ピストン５６８をシリンダ５６６内に置く。必要であれば、追加の限定おもりをピストン・チャンバ５９０内に置く。
８）ガラス・フリット５０２を穿孔フィルムで被覆する。
９）この時点での図り読み値はゼロ若しくは風袋読み値を確定する。
１０）ガラス・フリット５０２を２００ｃｍへ移動させる。
１１）活栓５０９及び５１０を開き（活栓５１０は液体リザーバ５０５に対しては閉じられている）、はかり及び時間の読み取りを開始する。
【０４１８】
＜ガラス・フリットの補正（ブランク補正取り込み量）＞
ガラス・フリット・ディスク５６０は多孔性構造であるので、ガラス・フリット（５０２）毛管吸着吸収取り込み量（ブランク補正取り込み量）を測定し、真の試験サンプル毛管吸着吸収取り込み量を入手するために減じなければならない。ガラス・フリット補正は、使用される各新規ガラス・フリットについて実施する。ブランク取り込み量（ｇ）を入手するために、試験サンプルを使用しないこと以外は上記の通りに毛管吸着試験手順を実行する。各規定高さでの経過時間はブランク時間（ｓ）に等しい。
【０４１９】
＜蒸発損失の補正＞
１）ガラス・フリット５０２をゼロの２ｃｍ上方へ移動させ、それをこの高さで活栓５０９及び５１０を開いて（リザーバ５０５へは閉じて）３０分間平衡化させる。
２）活栓５０９及び５１０を閉じる。
３）Ｔｅｆｌｏｎ（登録商標）リング５６２をガラス・フリット・ディスク５６０の表面上に置く。Ｏリング５６４をＴｅｆｌｏｎ（登録商標）リングの上に置く。予備加熱したシリンダ５６６をＴｅｆｌｏｎ（登録商標）リング上に同心性に置く。ピストン５６８をシリンダ５６６内に入れる。穿孔フィルムをガラス・フリット５０２上に置く。
４）活栓５０９及び５１０を開き（リザーバ５０５へは閉じて）、３．５時間に渡ってはかり読み値及び時間を記録する。下記のようにサンプル蒸発量（ｇ／ｈｒ）を計算する：
［１時間後のはかり読み値−３．５時間後のはかり読み値］／２．５時間
上記の注意すべてを守った後でさえ、幾らかの蒸発損失、試験サンプル及びフリット補正両方について典型的には約０．１０ｇ／ｈｒが発生するであろう。理想的には、サンプルの蒸発は各々新たに据え付けられたガラス・フリット５０２について測定する。
【０４２０】
＜装置の洗浄＞
ガラス・フリット５０２を新たに据え付けたときには新規のＴｙｇｏｎ（登録商標）チューブ５０３を使用する。ガラスチューブ５０４及び５１１、液体リザーブ５０５、及びはかり付き液体リザーバ５０６は、細菌汚染が目に見える場合には蒸留水中で５０％Ｃｌｏｒｏｘ Ｂｌｅａｃｈ（登録商標）を用いて洗浄し、その後蒸留水ですすぎ洗いする。
【０４２１】
ａ．各実験後の洗浄
各実験の終了時に（試験サンプルが取り除かれた後）、ガラス・フリットは、ガラス・フリット・ディスクの孔から残留試験サンプルを除去するために液体リザーバ５０５から２５０ｍｌ試験液を用いて前方へフラッシュする（即ち、試験液がガラス・フリットの底部へ導入される）。活栓５０９及び５１０を液体リザーバ５０５に対して開き、はかり付き液体リザーバ５０６に対して閉じ、ガラス・フリットをその支持具から取外し、上下を逆にして最初は試験液を用いてすすぎ洗い、次にアセトン及び試験液（合成尿）を用いてすすぎ洗いする。すすぎ洗い中、ガラス・フリットは上下を逆に傾けて置かなければならず、すすぎ液はガラス・フリット・ディスクの試験サンプル接触面上へ噴出させる。すすぎ洗い後、ガラス・フリットは２５０ｍｌ試験液（合成尿）を用いて前方へ２度目のフラッシュ洗浄をする。最後に、ガラス・フリットは支持具に再び取り付け、フリット表面を水平にする。
【０４２２】
ｂ．ガラス・フリット性能の監視
ガラス・フリットの性能は、各洗浄手順後及び各ガラス・フリットを新規に取り付ける毎に０ｃｍ位置でのガラス・フリットセットアップを用いて監視しなければならない。５０ｍｌの試験液を水平にされたガラス・フリット・ディスク表面（Ｔｅｆｌｏｎ（登録商標）リング、Ｏリング及びシリンダ／ピストンコンポーネントを装着せずに）上に注入する。試験液レベルがガラス・フリット・ディスク表面上方５ｍｍへ低下するために要した時間を記録する。この時間が４．５分間を超える場合は、定期的洗浄を実施しなければならない。
【０４２３】
ｃ．定期的洗浄
定期的に、（上記のフリット性能の監視の項を参照）ガラス・フリットは目詰まりを防止するために完全に洗浄する。すすぎ液は蒸留水、アセトン、蒸留水に溶解させた５０％Ｃｌｏｒｏｘ Ｂｌｅａｃｈ（登録商標）（細菌増殖を除去するため）及び試験液である。洗浄には、支持具からガラス・フリットを取り外すこと及びすべてのチューブの接続を切り離すことが含まれる。ガラス・フリットは、適切な液体及び量を下記の順序で用いてフリットを上下逆にして前方へフラッシュ洗浄する（即ち、試験液がガラス・フリットの底部に導入される）：
１．２５０ｍｌの蒸留水
２．１００ｍｌのアセトン
３．２５０ｍｌの蒸留水
４．１００ｍｌの５０：５０Ｃｌｏｒｏｘ（登録商標）／蒸留水溶液
５．２５０ｍｌの蒸留水
６．２５０ｍｌの試験液
洗浄手順は、ガラス・フリットの性能が設定された流量基準（上記参照）内にあり、さらにガラス・フリット・ディスク表面上に残留物を観察できない場合には申し分がない。洗浄を良好に遂行できない場合は、フリットを交換しなければならない。
【０４２４】
＜計算＞
コンピュータは、各規定高さでのｃｍでの毛管吸引高さ、時間及びｇでの取り込み量から構成される報告を提供するようにセットアップする。このデータから、フリット取り込み量及び蒸発損失の両方について補正されている毛管吸引吸収容量を計算できる。同様に、０ｃｍでの毛管吸引吸収容量に基づいて、毛管吸収効率を規定高さで計算できる。さらに、２００ｃｍでの初期有効取り込み率が計算される。
【０４２５】
ブランク補正取り込み量：
ブランク補正取り込み量（ｇ）
＝ブランク取り込み量（ｇ）−ブランク時間＊サンプル蒸発量（ｇ／ｈｒ）／３，６００（ｓ／ｈｒ）
毛管吸引吸着容量（「ＣＳＡＣ」）：
ＣＳＡＣ（ｇ／ｇ）
＝{サンプル取り込み量（ｇ）−（サンプル時間＊サンプル蒸発量（ｇ／ｈｒ）／３，６００（ｓ／ｈｒ））−ブランク補正取り込み量（ｇ）}／サンプルの乾燥重量（ｇ）
２００ｃｍでの初期有効取り込み率（「ＩＥＵＲ」）：
ＩＥＵＲ（ｇ／ｇ／ｈｒ）＝２００ｃｍでのＣＳＡＣ（ｇ／ｇ）／２００ｃｍでのサンプル時間（ｓ）。
【０４２６】
＜報告＞
一定の吸収性部材又は一定の高表面積材料について毛管吸着吸収容量（ＣＳＡＣ）を計算するためには各サンプルについて最低２回の測定値を入手し、各高さについて取り込み量を平均化しなければならない。
【０４２７】
これらのデータを用いて、各数値を計算することができる：
−ｃｍで表される材料が０ｃｍでのその容量（即ちＣＳＡＣ０）のｘ％を放出した毛管吸着脱離高さ（ＣＳＤＨｘ）；
−ｃｍで表される材料が０ｃｍでのその容量（即ちＣＳＡＣ０）のｙ％を放出した毛管吸着吸収高さ（ＣＳＡＨｙ）；
−特に高さゼロ（ＣＳＡＣ０）、及び３５ｃｍ、４０ｃｍ、その他の高さでの、単位ｇ｛液体の｝／ｇ｛材料の｝で表される一定高さｚでの毛管吸着吸収容量（ＣＳＡＣｚ）；
−ＣＳＡＣ０及びＣＳＡＣｚに対する数値の比率である、％で表される一定高さｚでの毛管吸着吸収効率（ＣＳＡＥｚ）。
【０４２８】
２種の材料（収集／分配材料として使用されるような第１材料及び液体貯蔵材料として使用される第２材料）が結合されている場合は、第２材料のＣＳＡＣ値（及び従って各ＣＳＡＥ値）は第１材料のＣＳＤＨｘ値から測定できる。
【０４２９】
＜ティーバッグ遠心分離容量試験（ＴＣＣ試験）＞
ＴＣＣ試験は特に高吸収性材料のために開発されてきたが、これは他の吸収性材料にも容易に適用できる。
【０４３０】
ティーバッグ遠心分離容量試験では、吸収性材料における液体保持の尺度であるティーバッグ遠心分離容量値を測定する。
【０４３１】
吸収性材料は、「ティーバッグ」内に入れ、２０分間０．９重量％の塩化ナトリウム溶液中に浸漬させ、その後３分間遠心分離する。保持された液体量対乾燥材料の初期重量の比率がその吸収性材料の吸収容量である。
【０４３２】
２４ｃｍ×３０ｃｍ×５ｃｍの寸法を有するトレイ内に蒸留水中の０．９重量％の塩化ナトリウム２リットルを注入する。液体充填高さは約３ｃｍでなければならない。
【０４３３】
ティーバッグ・パウチは６．５ｃｍ×６．５ｃｍの寸法を有し、ドイツデュッセルドルフにあるティーカン(Teekanne)社から入手可能である。パウチは標準台所用プラスチック袋密封装置（例、ドイツのクルスプ(Krups)社のバックパック２ プラス(VACUPACK2 PLUS)）を用いてヒートシール可能である。
【０４３４】
ティーバッグは部分的に注意深くカットすることによって開封し、その後計量する。＋／−０．００５ｇまで正確に計量した吸収性材料の約０．２００ｇのサンプルをティーバッグ内に入れる。このティーバッグをその後ヒートシーラーを用いて密封する。これはサンプル・ティーバッグと呼ばれる。空のティーバッグを密封し、ブランクとして使用する。
【０４３５】
サンプル・ティーバッグ及びブランク・ティーバッグをその後食塩水の表面上に載せ、完全に湿潤するようにへらを用いて約５秒間浸漬させる（ティーバッグは食塩水の表面上に浮くであろうが、その後完全に湿潤する）。直ちにタイマーをスタートさせる。
【０４３６】
２０分間の浸漬時間後、サンプル・ティーバッグ及びブランク・ティーバッグを食塩水から取り出し、各バッグが遠心分離機バスケットの外壁にくっ付くようにバウネッハト(Bauknecht) ＷＳ１３０、Ｂｏｓｃｈ ７７２ ＮＺＫ０９６又は同等の遠心分離機（２３０ｍｍ径）に配置する。遠心分離機の蓋を閉め、遠心分離機をスタートさせ、速度を１，４００ｒｐｍまで急速に上昇させる。遠心分離機が１，４００ｒｐｍで安定したら、タイマーをスタートさせる。３分後、遠心分離機を停止させる。
【０４３７】
サンプル・ティーバッグ及びブランク・ティーバッグを取り出し、個別に計量する。
【０４３８】
吸収性材料のサンプルについてのティーバッグ遠心分離容量（ＴＣＣ）は次のように計算する：
ＴＣＣ＝［（遠心分離後のサンプル・ティーバングの重量）−（遠心分離後のブランク・ティーバングの重量）−（乾燥時吸収性材料重量）］÷（乾燥時吸収性材料重量）
さらに、「区分」カットアウトのような構造又は全吸収体の特定部分も又測定できるが（即ち、その場合は構造又は製品全体の部品として見るが）、そのためにはカッティングは製品の縦軸の測定されたポイントでの製品の全幅に渡って行う。特に、上記のような「股領域」の定義によって、「股領域容量」を測定することが可能になる。その他のカットアウトを使用して「基礎容量」（即ち製品の特定領域の単位面積に含有される容量）を測定することができる。単位面積のサイズ（好ましくは２ｃｍ×２ｃｍ）に依存して、どの程度の平均化が起こるのかが決まる−当然ながら、サイズが小さいほどより少ない平均化が発生するであろう。
【０４３９】
＜最終貯蔵容量＞
吸収体の最終設計貯蔵容量を測定若しくは評価するために、数多くの方法が提案されてきた。
【０４４０】
本発明の状況では、製品の最終貯蔵容量は個別要素若しくは材料の最終吸収容量の合計であると仮定される。これらの個々のコンポーネントに対して、これらが比較を通して一貫して適用される限りにおいて様々な明確に確立された方法を適用することができる。例えば、高吸収性ポリマー（ＳＡＰ）のために開発されて明確に確立されたティーバッグ遠心分離容量試験はそうしたＳＡＰ材料だけではなく他の材料にも使用できる（上記参照）。
【０４４１】
個々の材料に対する容量が明らかになると、これらの数値（ｍｌ／ｇ）に製品に使用された材料の重量を掛けることによって総製品容量を計算することができる。
【０４４２】
液体の最終貯蔵以外の専用の機能性（収集層その他のような）を有する材料については、そうした材料は専用最終液体貯蔵材料と比較して実際に極めてほんの僅かな容量値しか有していないか、又はそうした材料は液体が負荷されることが意図されていない、従って他の最終貯蔵材料にそれらの液体を放出しなければならないような最終貯蔵容量は無視できる。
【０４４３】
＜密度／キャリパー／坪量測定＞
例えばサンプル・カッターを用いてカットした限定面積の試験片を少なくとも０．１％の精度まで計量する。５５０ｐａ（０．０８ｐｓｉ）の適用圧力下で５０ｍｍ径の試験面積についてキャリパーを測定する。ｇ／ｍ²で表される単位面積当たりの重量としての坪量、５５０Ｐａの圧力下でのｍｍで表されるキャリパー、及びｇ／ｃｍ³で表される密度は容易に計算できる。
【図面の簡単な説明】
【図１】 浸透率試験セットアップの様々な実行を示している。図１は面横断浸透率の測定の簡易試験に関する。
【図２】 浸透率試験セットアップの様々な実行を示している。図２は面内浸透率の簡易試験に関する。
【図３】 浸透率試験セットアップの様々な実行を示している。図３は面横断浸透率の測定の一般試験に関する。
【図４】 浸透率試験セットアップの様々な実行を示している。図４は面内浸透率の測定の一般試験に関する。
【図５】 毛管吸着試験台（キャプソープション）を示している。
【図６】 毛管吸着試験台（キャプソープション）を示している。
【図７】 毛管吸着試験台（キャプソープション）を示している。
【図８】 毛管吸着試験台（キャプソープション）を示している。
【図９】 吸収体の実施例としてのおむつを示している。[0001]
[General Field of the Invention]
The present invention relates to a hygienic absorbent body comprising a fluid distribution member, such as a disposable baby diaper, training pants, an adult urinary incontinence pad, a feminine hygiene product, and the like that exhibits improved performance for distributing liquid in such products. About.
[0002]
[Background / prior art]
In the general field of disposable absorbents and structures, materials that exhibit well-defined fluid distribution characteristics are well known. Such materials, also called Absorbent Gelling Materials or superabsorbent materials or superabsorbents, which provide a good means for storing aqueous liquids such as urine, are the introduction of highly absorbent materials. Has become increasingly important, but does not enhance fluid transport, when suboptimal designs and / or suboptimal materials are used, and often referred to as “gel blocking” If the so-called phenomenon occurs, even a drop in liquid transport may occur. For example, in a structure where the superabsorbent is intimately mixed with cellulosic fibers, a certain critical concentration that is strongly influenced by the choice of the superabsorbent material must be exceeded in order not to deteriorate the effectiveness of the absorbent core. There must not be.
[0003]
As a result, a very large number of absorbent core designs have individual functions, for example by providing not only liquid storage areas or materials but also areas with special properties to enhance fluid collection and / or distribution. And has appeared. Often, one area was aimed at enhancing collection and distribution at the same time.
[0004]
Initially, the requirements for the dispensing material are not very high, for example standard tissue paper materials used for wrap sheets in the core, eg as described in US Pat. No. 3,952,745 (Duncan) It has also been applied to enhance fluid distribution as described in patent 0 343 941 (Reising) or US Pat. No. 4,578,068 (Kramer).
[0005]
Subsequent developments include EP-A-0,397,110 (Latimer), which discloses an absorber with a surge management portion having a specific basis weight, collection time and residual moisture to improve fluid handling. U.S. Pat. No. 4,898,642 (Moore et al.) Discloses specially twisted and chemically cured cellulosic fibers and absorbent structures made therefrom; European Patent No. A-0,640,330 (Bewick Sonntag et al.) Discloses the use of such fibers in specific configurations using special superabsorbent materials.
[0006]
A further approach is aimed at improving the wicking properties of cellulosic equipment, such as US Pat. No. 3,575,174 or US Pat. No. 4,781,710, along the wicking line or closed. In order to increase the wicking height in the mesh pattern, the structure is compressed to form smaller holes.
[0007]
Since some of these materials exhibit an undesirable hard feel, methods for post-formation processing to improve softness are well known. “Post-formation treatment” means after forming and drying the tissue (instead of or in addition to increasing softness during the manufacture or formation of the tissue), eg, to form an absorbent core or product, often. This means the fact that the tissue is mechanically processed in individual process steps just prior to other processing, such as the step of combining tissue with other materials. Examples of such treatment are US Pat. No. 5,117,540 (Walton) or US Pat. No. 4,440,597 (Wells).
[0008]
Another attempt to significantly affect the pore size of the distribution material is to reduce the maximum pore size by stretching the fiber structure with fibers that can be melted in one direction and then “freezing” the deformation by heat curing. The intended US Pat. No. 5,244,482 (Hassenboehler).
[0009]
Furthermore, special material composites have been developed with the aim of being able to adjust the pore size and pore size distribution according to the purpose. Examples of such improvements are described in great detail in US Pat. No. 5,549,589 (Horney et al.) Or PCT application WO 97/38654 (Seger et al.). Both essentially fill the larger pores with small and fine cellulosic fibers such as eucalyptus fibers by using specially cured cellulosic fibers such as cross-linked cellulosic softwood fibers. The purpose is to provide a resilient structure. In both patent applications, the first (US Pat. No. 5,549,589) is the second (WO 97/38654) by adding thermoplastic fibers and further partially melting them. Adding means to provide sufficient integrity and strength to the structure by adding chemical binders.
[0010]
Another approach, such as that disclosed in European Patent Application EP-A-0,810,078 (d'Acchioli et al.), Is thereby explained by a higher liquid outflow ratio at a constant wicking height. Special post-molding mechanical processing of the web is used to provide such improved fluid processing characteristics.
[0011]
In the hope of improving the functionality of the absorber, more specific requirements for distribution materials have emerged so that porous materials can be studied in more detail. To improve the longitudinal fluid distribution, high surface area synthetic fibers were applied to the absorbent structure as described, for example, in US Statuary Invention Registration H1511. Another class of materials is foamable structures such as cellulosic foams such as are commercially available by Spontex SA (France).
[0012]
Other polymer foams for use in the absorbent are disclosed in US Pat. No. 5,268,224 (DesMarais), ie high internal phase polymer materials, but they are used to store liquids And at the same time has the ability to avoid local saturation by spreading the storage liquid throughout the material.
[0013]
However, all these studies have so far been aimed at improving the wicking properties of the dispensing material, such as flow rate, wicking height and wicking time, but are important in the absorber, for example, between multiple loads. In some cases, especially when such materials are not fully saturated, the importance of the dewatering mechanism of the dispensing material by the liquid storage material has not been recognized.
[0014]
OBJECT OF THE INVENTION
Accordingly, one object of the present invention is to provide an improved absorbent body having an improved dewatering function of the distribution member, particularly under low saturation conditions.
[0015]
Another object of the present invention is to provide an improved absorber comprising a material that can transport liquid throughout the absorber, even when saturated to low or medium saturation.
[0016]
Yet another object of the present invention is to provide such a product comprising a liquid storage material having even better capillary absorption performance.
[0017]
【Overview】
The present invention is an absorbent containing a fluid distribution member, the fluid distribution member having a substantially high permeability even in subsaturated conditions, and a fluid storage in liquid communication with the distribution member in the product It has a low Capillary Sorption Absorption Height at 50% of its capacity at 0 cm of the member, which is the Capillary Adsorption Desorption Height at 50% of its capacity at 0 cm of the fluid storage member. Higher than Sorption Desorption Height).
[0018]
Thus, the distribution member has a permeability at 50% of its saturation, which is at least about 14% or more, preferably 18% or more, even more preferably 25% or 35% or more of the permeability at 100% saturation. It is.
[0019]
Accordingly, the first fluid storage member has a CSAH of about 15 cm or more, preferably about 23 cm or more, even more preferably about 27 cm or more, or more preferably about 30 cm or more, and most preferably about 47 cm or more.
[0020]
In another preferred embodiment, the absorber comprises a fluid distribution member that has a permeability at 30% of its saturation, i.e., k (30), which is about 3 of k (100). % Or more, preferably about 5% or more, more preferably about 10% or more of k (100).
[0021]
In another preferred embodiment, the fluid distribution member has a CSDH50 value of less than about 150 cm, more preferably less than about 100 cm, even more preferably less than about 75 cm, and most preferably less than about 50 cm.
[0022]
In one particularly preferred embodiment, the fluid distribution member comprises an open cellular foam that can expand when wet and can collapse again upon discharge of liquid, more preferably the distribution member is of the HIPE type. It has an interconnected open cell hydrophilic and flexible polymer foam structure.
[0023]
In yet another embodiment, the absorber has at least two liquid storage areas, both liquid storage areas being in liquid communication with the fluid distribution member, but preferably at least one of said liquid storage areas is A material exhibiting a capillary adsorption absorption height (CSAH50) at 50% of its maximum capacity of at least about 40 cm.
[0024]
In yet another embodiment of the invention, an absorbent body having such a distribution member can be described by one crotch region and one or more torso regions, wherein the crotch region is a combination of the one or more torso regions. Also has a lower final liquid storage capacity, which is less than 0.9 times the average final fluid storage base volume of the absorbent core, more preferably less than 0.5 times the average final fluid storage base capacity of the absorbent core, and More preferably it can be described by having less than 0.3 times the average final fluid storage base capacity of the absorbent core.
[0025]
In yet another embodiment, the absorbent is a section of less than 49% of the total core final liquid storage capacity, preferably less than 41% of the total core final liquid storage capacity, and even more preferably less than 23% of the total core final liquid storage capacity. It has a crotch region with a final liquid storage capacity.
[0026]
In yet another embodiment of the present invention, the absorbent has a final liquid storage material that provides at least 80% of the total final storage capacity of the absorbent core, preferably 90% or more of the total final storage capacity of the absorbent core. .
[0027]
In yet another embodiment of the invention, the absorbent body has a very low absorption capacity in the crotch region, but preferably at least 50% of the crotch region is essentially free of final storage capacity.
[0028]
In addition, the absorbent body can place less than 50% of the final storage capacity forward from the crotch zone in the front half of the product, and more than 50% of the final storage capacity can be placed in the rear half of the product. it can. Even more preferably, the absorbent body can place less than 33% of the final storage capacity forward from the crotch zone in the front half of the product, and more than 67% of the final storage capacity is placed in the rear half of the product. be able to.
[0029]
[Detailed description]
As used herein, the term “fluid treatment member” typically relates to an absorbent component that provides at least liquid treatment functionality. The absorbent body may comprise one or more various fluid treatment members such as, for example, one or more liquid collection members, one or more fluid distribution members, and / or one or more fluid storage members. Each of these members can comprise one or more subelements that may or may not be homogeneous. That is, each member can be made from one material or several materials. For example, such a member may optionally be composed of sublayers and / or layers having arbitrarily different compositions, densities, or thicknesses.
[0030]
Each of these members can have a special function, for example, primarily providing a collection function or primarily providing a liquid storage function. Alternatively, the member may have multiple functions, such as a very early “cellulose only” diaper in which, for example, cellulose fluff performs simultaneous collection, distribution and final storage functionality.
[0031]
"Storage absorbent member" relates to an absorbent member with an absorbent core that primarily functions to ultimately store the absorbed liquid.
[0032]
A “fluid dispensing member” in the sense of the present invention is a member that meets the requirements described for fluid dispensing functionality, regardless of whether the member also has other liquid handling functions.
[0033]
“Liquid collection member” means a part or absorbent core that is primarily designed to contain liquid as it reaches the absorber.
[0034]
As used herein, the term “absorbent core” refers to an absorbent member that plays a central role in the liquid treatment of the product and thus includes “fluid treatment member”. In certain cases, the topsheet may be considered to provide, for example, a particular liquid collection performance, but the absorbent core itself typically does not include an absorbent topsheet or backsheet.
[0035]
Absorbent cores can be divided into “regions” of the core, but such “regions” can perform the functionality of one or more members outlined above. Thus, the collection region can comprise a collection member (and can also comprise other members) and can comprise a collection member (and only) that can be constructed from the collection material. Alternatively, the collection / distribution region can comprise both a collection member and a distribution member.
[0036]
As used herein, the term “absorber” refers to a device that absorbs and contains bodily excretion, and more particularly, to the wearer's body to absorb and contain various excretions excreted from the body. The present invention relates to a tool that is brought into contact with or disposed in the vicinity. The term “body fluid” as used herein includes, but is not limited to, urine, menstruation, vaginal discharge, sweat and stool.
[0037]
The term “disposable” is not intended to be washed as an absorbent or otherwise restored or reused (ie, discarded after use and preferably recycled, composted or otherwise compatible with the environment) Used to describe an absorber) that is intended to be disposed of in a manner.
[0038]
As used herein, the term “Z dimension” relates to a dimension orthogonal to the length and width of a member, core or product. The Z dimension usually corresponds to the thickness of the member, core or product. As used herein, the term “XY dimension” relates to a plane perpendicular to the thickness of a member, core or product. The XY dimensions usually correspond to the length and width of each member, core or product.
[0039]
As used herein, the term “region” or “zone” relates to a portion or section of the absorbent member. Thereby, the region or zone may be two-dimensional (front / rear) or three-dimensional (like a collection region having a three-dimensional extension even if it is in the form of a layer).
[0040]
As used herein, the term “layer” relates to an absorbent member whose primary dimension is XY, ie, an absorbent member having a primary dimension along its length and width. It should be understood that the term “layer” is not necessarily limited to a single layer or sheet of material. Thus, the layer can comprise a laminate or combination of several sheets or webs of the required type of material. Thus, the term “layer” includes the terms “layers” and “layered”.
[0041]
For the purposes of the present invention, the term “above” should be understood to refer to an absorbent body, such as the layer closest to the wearer of the absorbent body, and more typically the layer facing the absorbent topsheet. On the contrary, the term “downward” relates to an absorbent member that is furthest away from the wearer of the absorbent body and that typically faces the backsheet.
[0042]
All percentages, ratios and ratios used herein are calculated by weight unless otherwise indicated.
[0043]
<Absorber-General description>
The absorber generally comprises:
An absorbent core or core structure (which may comprise an improved fluid distribution member according to the invention and may further comprise a substructure);
A liquid permeable topsheet;
-Liquid impervious backsheet:
Optionally further features such as closure elements or resilience.
[0044]
FIG. 9 is a plan view of an exemplary embodiment of the absorbent body of the present invention which is a diaper.
[0045]
The diaper 20 is flattened in FIG. 9 so that the structure of the diaper 20 is more clearly shown and the outer surface 52 not facing the wearer makes the person looking at the view unnoticeable. Is shown in a non-shrinked state (i.e., the elasticity-induced contraction is stretched except for the side panels that remain elastic in the relaxed state). As shown in FIG. 9, the diaper 20 is preferably a liquid permeable topsheet 24, a liquid impervious backsheet 26 bonded to the topsheet 24, and between the topsheet 24 and the backsheet 26. A closed system comprising a double tension fastening system, generally designated as 36, and an absorbent core 28 disposed in the body; a resilient side panel 30; a resilient leg cuff 32; an elastic body feature 34; A containment assembly 22. The double tension fastening system 36 preferably comprises a primary fastening system 38 and a barrel closure system 40. The primary fastening system 38 preferably comprises a pair of fixing members 42 and landing members 44. It is shown in FIG. 9 that the torso closure system 40 preferably comprises a pair of first attachment component 46 and second attachment component 48. The diaper 20 further comprises an alignment patch 50 that is preferably disposed below each first mounting component 46.
[0046]
As shown in FIG. 9, the diaper 20 faces the outer surface 52 (facing the person viewing FIG. 9), the inner surface 54 on the opposite side of the outer surface 52, the first body region 56, and the first body region 56. It has a matching second body region 58 and an outer periphery 60 defined by the outer edge of the diaper 20, where the longitudinal edge is designated 62 and the edge is designated 64. The inner surface 54 of the diaper 20 includes a portion of the diaper 20 that is disposed adjacent to the wearer's body during use (ie, the inner surface 54 is generally coupled to at least a portion of the topsheet 24 and the topsheet 24). Formed from other components). The outer surface 52 comprises a portion of the diaper 20 that is positioned away from the wearer's body (ie, the inner surface 52 is generally formed from at least a portion of the backsheet 26 and other components coupled to the backsheet 26. ) The first body region 56 and the second body region 58 each extend from the edge 64 of the outer periphery 60 to the transverse center line 66 of the diaper 20. Each torso region includes a central region 68 and a pair of side panels that typically comprise the outer portion of the torso region. The side panel disposed in the first body region 56 is designated by 70, while the side panel in the second body region 58 is designated by 72. Although a pair of side panels or each side panel need not be identical, they are preferably the other mirror image. The side panel 72 disposed in the second body region 58 may be stretchable in the transverse direction (ie, the elastic side panel 30). (The transverse direction (X direction or width) is defined as the direction parallel to the transverse centerline 66 of the diaper 20; the longitudinal direction (Y direction or length) is defined as the direction parallel to the longitudinal centerline 67. And the axial direction (Z direction or thickness) is defined as the direction extending through the thickness of the diaper 20.
[0047]
FIG. 9 illustrates the use of a diaper 20 having a length and width dimension where the topsheet 24 and backsheet 26 are generally larger than the topsheet and backsheet of the absorbent core 28. The topsheet 24 and backsheet 26 extend beyond the edges of the absorbent core 28 to thereby form the outer periphery 60 of the diaper 20. The outer periphery 60 defines the outer periphery, or in other words, the edge of the diaper 20. The outer periphery 60 includes a longitudinal edge 62 and an edge 64.
[0048]
Each resilient leg cuff 32 may be configured to resemble any of the leg bands, side flaps, barrier cuffs, or resilient cuffs described above, but each resilient leg cuff 32 may be constructed, for example, from U.S. Pat. No. 4, cited above. , 909, 803, at least an inner barrier cuff 84 having a barrier flap 85 and a spacing resilient member 86. In certain preferred embodiments, the resilient leg cuff 32 further includes one or more elastic strands 105 disposed on the outside of the barrier cuff 84 as described, for example, in US Pat. No. 4,695,278 cited above. With an elastic gas kettle cuff 104.
[0049]
Further, the diaper 20 may include an elastic body feature 34 that provides improved adaptation and containment. The elastic body feature 34 extends at least longitudinally outward from at least one of the body edges 83 of the absorbent core 28 at least in the central region 68 and generally forms at least a portion of the edge 64 of the diaper 20. To do. Accordingly, the elastic torso feature 34 comprises at least a diaper portion that extends from the torso edge 83 of the absorbent core 28 to the end edge 64 of the diaper 20 and is intended to be positioned adjacent to the wearer's torso. . Disposable diapers are generally configured to have two elastic body functions, one disposed in the first body region and the other disposed in the second body region.
[0050]
The elastic waistband 35 of the elastic waist feature 34 is disposed between a portion of the topsheet 24, preferably a portion of the backsheet 26 that is mechanically extended, and between the topsheet 24 and the backsheet 26. A double laminate material comprising an elastomeric member 76 and a resilient member 77 disposed between the backsheet 26 and the elastomeric member 76 can be provided.
[0051]
The diaper components as well as other components are described in further detail in WO 93/16669, incorporated herein by reference.
[0052]
<Absorbent core>
The absorbent core is generally compressible and comfortable, must be non-irritating to the wearer's skin, and must be able to absorb and retain fluids such as urine and certain body excretion. As shown in FIG. 9, the absorbent core has a garment surface (“lower” or “lower” portion), a body surface, a side edge, and a torso edge. In addition to the fluid distribution member according to the present invention, the absorbent core is, for example, ground wood pulp, commonly referred to as air felt; meltblown polymer containing coform; chemically cured, modified or cross-linked Cellulosic fibers; with a wide variety of liquid absorbent or liquid treatment materials commonly used in disposable diapers and other absorbent bodies, including but not limited to tissue paper including tissue wrap and tissue laminate be able to.
[0053]
General examples of absorbent structures are given in US Pat. No. 4,610,678 entitled “High-Density Absorbent Structures” issued September 9, 1986 to Weisman et al. U.S. Pat. No. 4,673,402 entitled “Abosrbent Articles With Dual-Layered Cores” issued to Weisman et al. On May 16, 2009; Angstadt on December 19, 1989 U.S. Pat. No. 4,888,231 entitled "Absorbent Core Having A Dusting Layer" issued to the U.S. Patent No. 0-0640 330; Bewick-Sontag et al. No. 5,180,622 (Berg et al.); US Pat. No. 5,102,597 (Roe et al.); US Pat. No. 5,387,207 (LaVon). Such structures and similar structures can be adapted to meet the requirements outlined below for use as the absorbent core 28.
[0054]
The absorbent core may be a single core structure, or it may be a combination of several absorbent structures that can in turn consist of one or more substructures. Each of the structures or substructures can have a substantially two-dimensional extension (ie, layer) or three-dimensional shape.
[0055]
<Absorber area>
In general, absorbent hygiene products are intended to be worn around the lower end of the fuselage. The essential design feature of these products is to cover the body area (“drain area”) where the discharge occurs, extending around each body opening. Each zone of the absorber covering the discharge area is correspondingly called a “load zone”. Thus, in use, the products are generally placed on the wearer so that they extend upwards from the crotch between the legs (relative to the wearer's standing posture) both before and after the wearer.
[0056]
In general, such products have a length dimension that exceeds their width dimension so that when the wearer is standing, the axis of the length dimension is aligned with the height direction of the wearer, The product is worn so that the width dimension of the product is aligned with the line extending from left to right of the wearer.
[0057]
Due to the human wearer's anatomy, the gap between the wearer's legs generally limits the gap available for the product in this area. In order to fit well, the absorber must also be designed so that it fits well into the area. If the width of the product is too wide compared to the wearer's crotch width, the product may be deformed, which may result in poor performance and reduced wearer comfort.
[0058]
The point at which the product has the smallest width to best fit between the wearer's legs coincides with the point on the wearer where the distance between the feet is the narrowest, and further within the scope of the present invention. It is called “Crotch Point”.
[0059]
If the crotch point of the product is not obvious from its shape, place the product in a standing position, preferably on the wearer of the intended user group (eg, a toddler child), and then the figure 8 shape It can be measured by placing a stretchable filament around the leg. The point of the product that corresponds to the intersection of the filaments is considered to be the crotch point of the absorbent core that is secured within the product and consequently the product.
[0060]
The crotch point of this product is often in the middle (in the longitudinal direction) of the product, but this is not always true. It can certainly be that the part in front of the product that is to be installed is smaller than the back (back) in either its length dimension, width, or both, or surface area. Similarly, the crotch point need not be located in the center of the absorbent core, particularly if the absorbent core is not centered longitudinally within the product.
[0061]
The crotch region is a region surrounding the crotch point so as to cover each body opening which is a discharge region. Unless otherwise stated, this region spans 50% of the length of the core (which is defined as the distance between the front and back barrel edges of the core approximating a straight line perpendicular to the longitudinal centerline). Is growing. When the crotch point is located in the center of the product, the crotch region (when taken into account from the core leading edge) starts at 25% of the total length of the core and extends to 75% of the total length of the core. Alternatively, the front and rear quarters of the length of the absorbent core do not belong to the crotch region and the rest belong to the crotch region.
[0062]
The crotch region length, which is 50% of the total length of the absorbent core, has been derived for baby diapers, but in this case it has been established that this is an appropriate means to explain the fluid treatment phenomenon. ing. When the present invention is applied to products with significantly different dimensions, these 50% are reduced (as in the case of severe urinary incontinence products) or this ratio is increased (very mild or mild urinary incontinence products) May be necessary). Broadly speaking, this crotch area of this product should not extend far beyond the wearer's drainage area.
[0063]
Even when the crotch point is offset from the center point of the product, the crotch region covers 50% of the total product length (in the longitudinal direction). However, in some cases, it is not evenly distributed between the front and the rear, and is adjusted in proportion to this deviation.
[0064]
As an example of a product having a total core length of 500 mm and a centrally located crotch point, the crotch region would extend from a position 125 mm away from the leading edge to a position 375 mm away from the leading edge. Or, if the crotch point is offset 50 mm towards the core leading edge (ie, 200 mm away from the core leading edge), the crotch region extends from 100 mm to 350 mm.
[0065]
Roughly speaking, L_cCore length, distance L from core leading edge_cpCrotch point away, and L_czFor products having a crotch zone length of the crotch zone, the leading edge of the crotch zone will be positioned at the following distance:
L_fecz= L_cp ^*(1-L_cz/ L_c)
For example, the absorbent body can be a baby diaper for a toddler to wear (ie, an infant weighing about 12-18 kg) whose size of the marketed product is commonly referred to as the MAXI size. In that case, the product must be able to accommodate and hold both stool and urine, whereas in the context of the present invention, the crotch region must be able to primarily accommodate urine loads.
[0066]
The total area and size of the crotch region naturally depends on the width of the absorbent core. That is, in the crotch region, when the core is narrower than the outside of the crotch region, the crotch region has an area (surface area) that is smaller than the remaining area of the absorbent core.
[0067]
Although it can be expected that the boundary between the crotch region and the rest of the product is curvilinear, they are estimated within the present description to be a straight line perpendicular to the longitudinal axis of the product.
[0068]
The “crotch region” is further limited by the width of the core in each region, and the “crotch region area” is further limited by the surface area as defined by the crotch region length and each width.
[0069]
As a complementary element for the crotch region, the absorbent core further comprises at least one, but at most two, a torso region extending toward the front and / or back of the absorbent core outside the crotch region. .
[0070]
<Design capacity and final storage capacity>
It has been discovered that “design capacity” is a suitable means because the absorbers can be compared for different end use conditions or for different sized products.
[0071]
For example, an infant represents a typical use group, but even within this group, the amount of urine load, the frequency of the load, and the composition of the urine are on the one hand from small infants (newborns) to toddlers and the other So, for example, it will vary quite widely between the various individual infants.
[0072]
Another group of users may be old-aged infants who are still in trouble with some form of urinary incontinence.
[0073]
In addition, adults with urinary incontinence can use such products under a wide range of loading conditions, from what is commonly referred to as mild urinary incontinence to the range of severe urinary incontinence.
[0074]
Those skilled in the art will be able to easily move this teaching to other sizes for more detailed discussion, but here we will focus on the toddler size. For such users, a urine load up to 75 ml per urination, a total load of 300 ml as a result of an average of 4 urinations per wearing period, and a urination rate of 15 ml / sec are well represented. It has been discovered that
[0075]
From there, such products that can address such requirements must have the ability to accommodate such amounts of urine, which in more detailed discussion is referred to as “design capacity”.
[0076]
These fluid volumes must ultimately be absorbed by body fluids, or at least those materials that can store these aqueous parts, so that little liquid remains on the surface of the product, if any, facing the wearer's skin. . The term “final” relates to situations like those in absorbent bodies that in some cases have a long wearing time, but in other cases to absorbent materials that reach their “final” capacity when equilibrated with their environment. This can be in such an absorber that is under real-use conditions after a long wearing time, or in a test method for a pure material or material composite. Many of the processes under consideration have asymptotic dynamic behavior, so that one skilled in the art will be “final” when the actual capacity reaches a value sufficiently close to the asymptotic end point, for example, compared to the instrument measurement accuracy. You will consider that capacity has been reached.
[0077]
The absorbent body can comprise materials that are primarily designed to ultimately store fluids, and other materials that are designed primarily to fulfill other functions such as fluid collection and / or distribution. As such, a suitable core material according to the present invention can be described without artificially attempting to separate such functions, since it can still have a certain final storage capacity. Nevertheless, the final storage capacity can be measured for the total absorbent core, its region, absorbent structure, or even the substructure, and also for the materials used in any of the above.
[0078]
As discussed above with respect to changing product dimensions, those skilled in the art will readily be able to adapt the appropriate design capacity for other groups of users.
[0079]
<Materials used in absorbent core>
The absorbent core for the present invention can comprise a fibrous material for forming a fibrous web or fibrous matrix.
[0080]
Fibers useful in the present invention include those that are naturally occurring fibers (modified or unmodified) as well as synthetically produced fibers. Suitable non-modified / modified naturally occurring fibers include cotton, esparto, bagasse, coarse wool, flax, silk, wool, wood pulp, chemically modified wood pulp, jute, rayon, ethyl cellulose, and cellulose acetate . Suitable synthetic fibers include polyvinyl chloride, polyvinyl fluoride, polytetrafluoroethylene, polyvinylidene chloride, polyacrylics such as ORLON®, polyvinyl acetate, polyethyl acetate, insoluble or soluble polyvinyl alcohol, polyethylene (Eg, PULPEX®) and polyolefins such as polypropylene, polyamides such as nylon, polyesters such as DACRON® or KODEL®, polyurethanes, polystyrenes and others be able to. The fibers used can comprise a naturally occurring fiber alone, a synthetic fiber alone, or any suitable combination of naturally occurring and synthetic fibers. The fibers used in the present invention may be hydrophilic or may be a combination of both hydrophilic and hydrophobic fibers.
[0081]
For many absorbent cores or core structures according to the present invention, the use of hydrophilic fibers is preferred. Suitable hydrophilic fibers for use in the present invention include cellulosic fibers, modified cellulosic fibers, rayon, polyester fibers such as polyethylene terephthalate (eg, DACRON®), hydrophilic nylon (HYDROFIL®). Trademark)). Suitable hydrophilic fibers are also hydrophobic, such as surfactant-treated or silica-treated thermoplastic fibers derived from polyolefins such as polyethylene or polypropylene, polyacrylics, polyamides, polystyrenes, polyurethanes and others. It can also be obtained by making the fibers hydrophilic.
[0082]
Suitable wood pulp fibers can be obtained from a number of well known chemical processes including, but not limited to, kraft and sulfite processes. Another suitable type of fiber is chemically cured cellulose. As used herein, the term “chemically cured cellulosic fiber” means a cellulosic fiber that has been cured by chemical means to increase the stiffness of the fiber under both dry and aqueous conditions. . Such means can include, for example, the addition of chemical curing agents that coat and / or impregnate the fibers. Such means may also include the step of curing the fibers by changing the chemical structure, for example by cross-linking the polymer chains.
[0083]
Polymeric curing agents that can coat or impregnate cellulosic fibers include: Nitrogen as available from National Starch and Chemical Corp. (Bridgewater, NJ, USA). Cationic modified starches having a content group (eg, amino group); latexes; polyamides which are polyacrylamide resins described in US Pat. No. 3,556,932 (Coscia et al.) Issued on January 19, 1971 Wet strength resin such as epichlorohydrin resin (eg, Kymene® 557H, Hercules, Inc. (Wilmington, Del., USA)); trademark of Parez® 631NC In American Cyanamid Co. (Stanford) Commercially available polyacrylamides sold by the United States, Connecticut; Urea formaldehyde and melamine formaldehyde resins, and polyethyleneimine resins.
[0084]
These fibers can also be cured by chemical reaction. For example, the crosslinking agent can be applied to fibers in which interfiber cross-linking is chemically induced following application. These crosslinks can increase the stiffness of the fiber. The use of interfiber crosslinks is preferred for chemically curing the fibers, but this does not mean excluding other types of reactions for chemically curing the fibers.
[0085]
Fibers cured by cross-linking in individualized form (i.e., individualized cured fibers and processes for preparing them) are described, for example, in U.S. Pat. No. 3, issued December 21, 1965. No. 224,926 (Bernardin); U.S. Pat. No. 3,440,135 issued on April 22, 1969 (Chung); U.S. Pat. No. 3,932,209 issued on Jan. 13, 1976. (Chatterjee); and US Pat. No. 4,035,147 issued December 19, 1989 (Sangenis et al.); US Pat. No. 4,898,642 d issued February 6, 1990 (Moore et al.). And U.S. Pat. No. 5,137,537 (Herron et al.) Issued Aug. 11, 1992.
[0086]
In presently preferred cured fibers, the chemical process involves interfiber cross-linking using a cross-linking agent, but such fibers are substantially dehydrated and the fibers are disaggregated (ie, individualized) and twisted and curled. . Suitable chemical curing agents are typically C, such as citric acid.₂-C₉A monomer crosslinking agent containing a polycarboxylic acid. Preferably, such cured fibers are twisted and curled as described in more detail in US Pat. No. 4,898,642.
[0087]
These chemically cured cellulosic fibers have certain properties that make them particularly useful in certain absorbent structures according to the present invention as compared to uncured cellulosic fibers. In addition to being hydrophilic, these cured fibers have a unique combination of stiffness and flexibility.
[0088]
Additionally or alternatively, the absorbent structure can be provided with synthetic or thermoplastic fibers such as those made from any thermoplastic polymer that can be melted at temperatures that do not extensively damage the fibers. Preferably, the melting point of the thermoplastic material will be less than about 190 ° C and preferably between about 75 ° C and about 175 ° C. In any case, the melting point of this thermoplastic material must never be lower than the temperature that would be stored when the heat bonded absorbent structure is used in the absorbent body. The melting point of the thermoplastic material is typically not less than about 50 ° C.
[0089]
Thermoplastic materials, and in particular thermoplastic fibers, are polyolefins such as polyethylene (e.g. PULPEX®) and polypropylene, polyesters, copolyesters, polyvinyl acetate, polyamides, copolyamides, polystyrenes, It can be made from a variety of thermoplastic polymers including polyurethanes and any of the above copolymers such as vinyl chloride / vinyl acetate and others. Suitable thermoplastic materials include hydrophilic such as surfactant-treated or silica-treated thermoplastic fibers derived from polyolefins such as polyethylene or polypropylene, polyacrylics, polyamides, polystyrenes, polyurethanes and others. Hydrophobic fibers are included. The surface of the hydrophobic thermoplastic fiber may be coated with surfactant as part of the polymer that is melted when, for example, spraying the surfactant onto the fiber, dipping the fiber into the surfactant, or making the thermoplastic fiber. By including it, it can be rendered hydrophilic by treatment with a surfactant such as a nonionic or anionic surfactant. Upon melting and resolidification, the surfactant will tend to stay on the surface of the thermoplastic fiber. Suitable surfactants include nonionic surfactants such as Brij® manufactured by ICI Americas, Inc. of Wilmington, Del. And the trademark of Pegosperse®. At Glyco Chemical, Inc. of Greenwich, Connecticut. The various surfactants sold by are included. In addition to nonionic surfactants, anionic surfactants can also be used. These surfactants can be applied to thermoplastic fibers, for example, at a level of about 0.2 to about 1 g per cubic centimeter of thermoplastic fiber.
[0090]
Suitable thermoplastic fibers can be made from a single polymer (monocomponent fibers) or can be made from one or more polymers (eg, bicomponent fibers). For example, a “bicomponent fiber” may refer to a thermoplastic fiber comprising a core fiber made from one polymer that is enclosed in a thermoplastic sheath made from a different polymer. Polymers with a sheath often melt at a lower temperature, typically different from polymers with a core. As a result, these bicomponent fibers provide thermal bonding due to the melting of the sheath polymer, while retaining the desirable strength characteristics of the core polymer.
[0091]
Bicomponent fibers suitable for use in the present invention can include sheath / core fibers having the following polymer combinations: polyethylene / polypropylene, polyethyl vinyl acetate / polypropylene, polyethylene / polyester, polypropylene / polyester, copolyester. / Polyester etc. Particularly suitable bicomponent thermoplastic fibers for use herein are those having a polypropylene or polyester core and a sheath of copolyester, polyethyl vinyl acetate or polyethylene that melts at lower temperatures (eg, DANAKLON®). ), CELBOND (registered trademark) or CHISSO (registered trademark) bicomponent fiber). These bicomponent fibers may be concentric or eccentric. As used herein, the terms “concentric” and “eccentric” relate to whether the sheath has a uniform or non-uniform thickness through the cross-section of the bicomponent fiber. Eccentric bicomponent fibers may be desirable when providing higher compressive strength when the fiber thickness is small. Bicomponent fibers suitable for use herein can either be crimped (ie, bent). Bicomponent fibers are typically crimped by typical textile means such as, for example, a stuffer boy method or gear crimp method to achieve primarily two-dimensional or “flat” crimping be able to.
[0092]
In the case of thermoplastic fibers, their length may vary depending on the specific melting point and other properties desired for these fibers. Typically, these thermoplastic fibers have a length of about 0.3 to about 7.5 cm, preferably about 0.4 to about 3.0 cm. The properties of these thermoplastic fibers including the melting point can be adjusted by changing the fiber diameter (caliper). The diameter of these thermoplastic fibers is typically defined by either denier (grams per 9,000 meters) or decitex (grams per 10,000 meters dtex). Depending on the particular arrangement within the structure, suitable thermoplastic fibers may have a decitex clearly in the range well below 1 dtex, for example 0.4 dtex to about 20 dtex.
[0093]
The fibrous material may be used in individualized form when an absorbent is manufactured and an airlaid fibrous structure is immediately formed. The fiber may also be used as a preform fiber web or tissue. . These structures will then be supplied to manufacture products that are substantially endless or very long (eg, on rolls, spools) and then cut to the appropriate size. This can be done individually for each such material when the core itself is cut and the material is coextensive with the core before they are combined with other materials to form an absorbent core. .
[0094]
There are a wide variety of ways to produce such webs, but such processes are clearly known in the art.
[0095]
In principle there are few restrictions on the fibers used to make such webs, but the process of molding and bonding certain specialty webs may not be completely compatible with certain materials or fiber types. is there.
[0096]
Looking at the individualized fibers as starting materials for making the web, they can be placed in a fluid medium-if it is gaseous (air), such a structure is generally "dry-laid" And when it is a liquid, such a structure is commonly called "wet-laid". “Wet-Laying” is widely used to produce tissue papers with a wide range of properties. The term is most commonly used with cellulosic materials, but synthetic fibers can also be included.
[0097]
“Dry-laying” is widely used for nonwoven webs, but carding processes can often be used to form such webs. Similarly, the commonly known “airlaid tissue” also falls into this category.
[0098]
The molten polymer can be extruded into fibers that can then be directly molded into a web (ie, the process steps to produce individual fibers that are then molded into the web in separate process steps are omitted). The resulting structure is generally referred to as a meltblown nonwoven, or a spunbonded web if the fibers are drawn out significantly more.
[0099]
In addition, the web can also be formed by combining one or more other forming technologies.
[0100]
These are generally combined to give the web structure certain strength and integrity characteristics. The most widely used technologies are (a) chemical bonding, or (b) thermal bonding by melting a portion of the web. For the latter, the fibers can be compressed to produce separate bond points that can cover a significant portion of the entire area, for example, 20% for nonwoven materials. Alternatively, an “air-through” bonding method can be applied, which is particularly useful for structures where low density is desired, in which case a portion of the polymer, eg a sheath material of BiCo fibers, passes through the (often air-laid) web. To be melted by heated air.
[0101]
After the web is formed and bonded, they can be further processed to modify certain properties. This may be an additional surfactant for making hydrophobic fibers more hydrophilic, or vice versa, as one of many possible examples. Similarly, post-molding mechanical processing such as disclosed in European Patent Application No. 96108427.4 can be used to impart particularly useful properties to such materials.
[0102]
In addition to or in place of the fibrous web, the absorbent core can also comprise other porous materials such as foam. A preferred foam is an open cellular absorbent polymer foam material such as is derived by polymerizing a high internal phase W / O (water-in-oil) emulsion (hereinafter referred to as HIPE). Such polymer foams can be shaped to provide the required storage properties as well as the required distribution properties.
[0103]
A HIPE-derived foam that provides both the necessary distribution and storage properties for use herein is a co-pending application filed November 25, 1995, the disclosure of which is hereby incorporated herein by reference. Patent application Ser. No. 08 / 563,866 (DesMarais et al.) (Hereinafter referred to as the “866 application”); a simultaneous application filed on October 13, 1995, the disclosure of each of which is hereby incorporated herein by reference. Pending US patent application Ser. No. 08 / 542,497 (Dyer et al.); US Pat. No. 5,387,207 issued on Feb. 7, 1995 (Dyer et al.); And November 9, 1993 It is described in issued US Pat. No. 5,260,345 (DesMarais et al.).
[0104]
The polymer foam useful in the present invention is relatively open-celled. This means that the individual cells of the form are in complete communication with neighboring cells without any interference. Cells in such a substantially open cellular foam structure are inter-cell openings or “windows” that are large enough to allow easy liquid movement within the foam structure from one cell to another. Have
[0105]
These substantially open cellular foam structures generally have a reticulated feature with individual cells defined by a plurality of interconnected three-dimensionally branched webs. . The strands of polymer material that make up these branched webs can be referred to as “struts”. The foam material used here is “open-cell” if at least 80% of the cells in the foam structure are at least 1 micrometer in size are in liquid communication with at least one adjacent cell.
[0106]
In addition to being open-celled, these polymer foams are sufficiently hydrophilic to allow the foam to absorb the amount of aqueous fluid specified below. The inner surface of the foam structure is rendered hydrophilic by residual hydrophilizing surfactant left in the foam structure after polymerization or by selected post-polymerization foam processing methods.
[0107]
The polymer foam can be prepared in a collapsed (ie, unexpanded) form, and the polymer foam expands to absorb such fluid when contacted with an aqueous fluid. See, for example, co-pending US patent application Ser. No. 08 / 563,866 and US Pat. No. 5,387,207. These collapsed polymer foams are typically obtained by squeezing the aqueous phase from the polymerized HIPE foam through compressive force and / or by thermal drying and / or vacuum dehydration. After compression and / or after heat drying and / or vacuum dehydration, the polymer foam is in a collapsed or unexpanded state. Alternatively, such foams are non-collapsible, such as described in co-pending applications, US patent application Ser. No. 08 / 542,497 and US Pat. No. 5,260,345. It may be a form.
[0108]
<Superabsorbent polymer or hydrogel>
Optionally and often preferably, the absorbent structure according to the present invention may comprise a superabsorbent polymer, or hydrogel. Hydrogel-forming absorbent polymers useful in the present invention include a variety of substantially water-insoluble, but water-swellable polymers that can absorb large amounts of liquid. Such polymeric materials are also commonly referred to as “hydrocolloid” or “superabsorbent” materials. These hydrogel-forming absorbent polymers preferably have a large number of anionic functional groups such as, for example, sulfonic acids, and more typically carboxyl groups. Examples of polymers that are suitable for use herein include those prepared from polymerizable unsaturated acid-containing monomers.
[0109]
Some non-acidic monomers can also be included, usually in small amounts, when preparing the hydrogel-forming absorbent polymer. Such non-acidic monomers include, for example, water-soluble or water-dispersible esters of acid-containing monomers and monomers that contain no carboxylic acid groups or sulfonic acid groups. Examples of such known materials are U.S. Pat. No. 4,076,663 (Masuda et al.) Issued on Feb. 28, 1978 and U.S. Pat. No. 4,062,817 issued on Dec. 13, 1977. (Westerman).
[0110]
Hydrogel-forming absorbent polymers compatible with the present invention contain carboxyl groups. These polymers include hydrolyzed starch-acrylonitrile graft copolymers, partially neutralized starch-acrylonitrile graft copolymers, starch-acrylic acid graft copolymers, partially Neutralized starch-acrylic acid graft copolymers, saponified vinyl acetate-acrylic ester copolymers, hydrolyzed acrylonitrile or acrylamide copolymers, mild of any of the above copolymers Network-crosslinked polymers, partially neutralized polyacrylic acid, and partially neutralized polyacrylic acid lightly cross-linked polymers. These polymers can be used either alone or in the form of a mixture of two or more different polymers. Examples of these polymeric materials are US Pat. No. 3,661,875, US Pat. No. 4,076,663, US Pat. No. 4,093,776, US Pat. No. 4,666,983, and US This is disclosed in Japanese Patent No. 4,734,478.
[0111]
The most preferred polymeric materials for use in making hydrogel-forming particles are partially neutralized polyacrylic acid lightly crosslinked polymers and their starch derivatives. Most preferably, the hydrogel-forming particles comprise from about 50 to about 95%, preferably about 75% neutralized, lightly network crosslinked polyacrylic acid (ie, sodium polyacrylate / polyacrylic acid). .
[0112]
As mentioned above, the hydrogel-forming absorbent polymer is preferably lightly cross-linked. The network crosslinks serve to make the polymer substantially insoluble in water and further determine, in part, the absorption capacity and extractable polymer content characteristics of the precursor particles and the resulting macrostructure. Processes for network cross-linking of polymers and typical network cross-linking agents are described in greater detail in US Pat. No. 4,076,663 and German Patent A-4,020,780 (Dahmen), cited above. Are listed.
[0113]
The superabsorbent material can be used in particulate or fibrous form and can also be combined with other elements to form a preform structure.
[0114]
Although individual elements have been disclosed individually so far, an absorbent structure or substructure can be made by further combining one or more of these elements.
[0115]
Without intending to have a limiting effect, the following describes the appropriate combinations:
i) Special superabsorbent polymer (SAP) mixed with cellulosic or other fibers. Although the basic principles are well established and well known, SAP-to-fibers are being used in ever-increasingly higher weight ratios in an attempt to reduce product thickness. Within the scope of the present invention, SAP and binders such as hot melt adhesives (for example disclosed in EP-A-0,695,541) or fusible polymer materials (for example PE particles). The combination with may be an appropriate tool to immobilize the SAP;
ii) SAP that forms a substructure by interparticle cross-linking;
iii) Fibrous SAP mixed with other fibers or forming a fibrous SAP web;
iv) A foam structure having different pore sizes and the like.
[0116]
<Improved absorber>
Having generally described the absorbent body and appropriate members, materials, structures, components and subcomponents, the following is a requirement for fluid storage members and fluid distribution members according to the present invention and adapted for use with such members The material to be used will be described.
[0117]
<Improved distribution member>
The requirements for the dispensing member can be determined by looking at either the member or the material contained in the member. Accordingly, the requirements listed in this description must be met for all members or each material therein.
[0118]
Thus, a dispensing member or material useful for such a member according to the present invention can be described by the following important parameters:
First, the permeability (k100) of the member or material at full saturation. Conventional dispensing materials have low resistance to liquid flow (ie, high permeability) and sufficient capillary pressure to provide, for example, wicking properties (ie, low permeability) as a result of smaller pore sizes. This permeability was balanced so that the optimal value between and could be found. Permeability (k100) at full saturation is generally greater than 1 Darcy (1 Darcy is 9.869)^*10^-13m²Preferably 2 Darcy or more, or even 8 Darcy or more, or even more preferably 100 Darcy or more. Complete saturation can be measured as the maximum uptake corresponding to the result of the capillary absorption capacity at 0 cm height (CSAC0) by a Capsorption test as described below.
[0119]
Second is the dependence of permeability on saturation. This property has not been taken into account in previous material design considerations, and conventional materials have a behavior that is not significantly proportional. That is, the actual permeability at less than 100% saturation is significantly lower than that obtained for the linear relationship between actual permeability and saturation.
[0120]
Third, the capillary adsorption pressure, that is, the capillary adsorption / desorption pressure as measured in the capillary absorption test described below. This parameter describes the ability of the material or member to release liquid to fulfill their role as a distribution element in the absorber.
[0121]
In addition, and often preferably, the dispensing material may meet high liquid outflow ratio requirements in a vertical wicking flow test as described below. Preferably, the material is at least 0.045 g / cm at a wicking height of 15 cm.²/ Sec, preferably 0.06 g / cm²/ Sec or more, more preferably 0.10 g / cm²Provides a flow rate of at least / sec.
[0122]
Careful selection of materials that meet the correct balance of these parameters can realize significant advantages for the absorbent structure and / or each product.
[0123]
First, the fluid dispensing materials are easily dehydrated after they are loaded, such as in the case of a urine jet. This is important in order to be ready to accept subsequent loads as these materials often occur in real use.
[0124]
Second, these materials allow for a more uniform fluid distribution of the liquid, even at loads that are significantly smaller compared to the design capacity. This is intended to maintain an improved fit for the wearer by avoiding a high degree of liquid accumulation in certain areas of the product, but rather a design aimed at even distribution of the stored liquid More important for.
[0125]
Third, if the material meets the higher flow requirements, the liquid can be dispensed well and quickly even against gravity. This becomes particularly important when the final storage of the liquid is intended to be remote from the load zone or region. Thus, these materials are particularly useful in core designs such as those described in PCT application US Ser. No. 97/05046, filed Mar. 27, 1997.
[0126]
The permeability of the material or member is measured by the permeability test described below.
[0127]
Without being bound by theory, the actual permeability k {S} has a dependence on saturation that can be approximated by the following equation for many related systems (according to J. Bear, Haifa). "Dynamics of fluids in porous media", publisher Dover Publications, Inc., New York, 1988, especially pages 461 and later, see also 491 and later):
k {S} = k {100}^*{S^SDP}
Where k represents the permeability in Darcy units; and SDP represents an infinite exponent or saturation dependent parameter that accounts for non-proportional behavior. S means a degree of saturation in the range of 0 to 1, where the value 1 corresponds to full saturation (ie 100% saturation) under zero external pressure and / or capillary pressure.
[0128]
Conventional design criteria for distribution materials have focused on high values for permeability at saturation (k100), but this naturally results in structures that have little or no wicking capability. I will. Thus, while a substantially “free flow regime” is suitable as a collection material that should be controlled, this is not the case with dispensing materials. Such materials will have very poor transport properties under wicking conditions, for example transport against gravity. Such extreme properties are found in conventional collection materials. Dispensing materials as described in European Patent Application No. A-0.809,991 provide a combination of wicking capability and free flow control, but also under fully saturated conditions.
[0129]
The material according to the invention exhibits a permeability k (100) of at least 1 Darcy, preferably at least 2 Darcy. Higher permeability values provide more resistance to liquid transport and are preferred as long as this is achieved as long as the other requirements listed here are not violated. In particular, a material having a permeability of 8 Darcy or higher, or even 100 Darcy or higher may be very suitable.
[0130]
As can be read from the equation, higher numbers for the SDP parameters account for systems that have a significantly more off-proportional behavior (if SDP is equal to 1, a linear relationship will exist). Conventional distribution materials behave significantly out of proportion, as can be explained by SDP having a numerical value of 3 or higher. For such numbers, the permeability at 50% saturation is only 12.5% of the permeability at 100% saturation, thus dramatically reducing the ability to accommodate and distribute more liquid loads. .
[0131]
Thus, the material according to the present invention has an SDP value of less than 3, preferably less than 2.75, more preferably less than 2.5, and a numerical value of less than 2 is even better. Such a numerical value corresponds to a permeability of 50% saturation of 14% or more, preferably about 18% or more, more preferably about 25% or more of the permeability at 100% saturation, and a value of 35% or more is even better. . Such a numerical value corresponds to a permeability at 30% saturation of about 3.5% or more, preferably about 5% or more, more preferably about 10% or more of the permeability at 100% saturation.
[0132]
The simple permeability test described below can also measure “cross-plane” permeability, ie, “in-plane” permeability, using the measured sample thickness dimension and modified sample cell. For example, for many materials such as isotropic foams, the cross-plane and in-plane permeability will be essentially the same. This simple permeability test provides a simple test mechanism for measuring permeability for two special conditions: a wide range of porous materials (100% saturated non-woven or cellulosic structures) Such as), or without filling with air (each for the outer vapor phase) with different proportionalities in the caliper to reach different saturations and facilitate penetration at different saturations at different thicknesses The permeation rate can be measured for materials that can be measured quickly.
[0133]
For example, the collapsible foam described above exhibits a thickness or caliper that depends on the liquid loading or degree of saturation. That is, they are saturated and have a constant thickness, which decreases when the liquid is removed, because the foam pores are sized so that they collapse when the liquid is removed from them. is there. Conversely, a constant caliper can be set to define a constant load. Thus, for such materials, a simple permeability test can be easily applied to measure the dependence of permeability on saturation.
[0134]
The general permeability test described below is the permeability to saturation for porous materials in the general sense, for example, a fibrous web or structure, or a foam that maintains pore size essentially independent of wetness. Useful for measuring the dependence of
[0135]
Another important requirement for a material or member according to the present invention is its ability to release fluid into the storage medium. This is due to the fact that the dispensing material or member should not hold the liquid for too long, but only for the time necessary to transport the fluid to the appropriate storage material or member. Is reflected.
[0136]
A suitable parameter to describe this property is the capillary adsorption / desorption pressure (here water column height (“capillary height”)) determined by the ability of the member to contain and discharge liquid at various capillary pressures. Which is typically encountered when the member is placed in the absorbent body. The capillary adsorption capacity test (hereinafter also referred to as the capsorption test) is per gram of absorbent member or material that is absorbed or released when the material or member is placed at various heights on the capillary adsorption device. Measure the amount of the test solution. The capillary adsorption / absorption capacity test, described in more detail in the Test Methods section below, produces a capillary adsorption / desorption height (CSDH50) where the material releases 50% of the liquid volume at 0 cm adsorption height.
[0137]
Materials useful in the context of the present invention should have a CSDH50 of less than 150 cm, preferably less than 100 cm, more preferably less than 75 cm or less than 50 cm.
[0138]
A particularly useful material for use in the present invention is a hydrophilic and flexible interconnected open cell polymer foam structure.
[0139]
For such foams, the mechanical strength of the foam may be such that upon release of the liquid, the foam collapses under the relevant capillary pressure. This collapse process reduces the effective capacity of the foam by a substantial factor related to the density of the foam, as described below. If the collapse is relatively uniform throughout the structure, it also reduces the amount of liquid retained at that location at the liquid impact point. In this connection, the strength of the foam is less than the capillary pressure exerted by the foam, so that the foam collapses when the aqueous liquid is removed by the core storage component. The capillary pressure is here controlled primarily by adjusting the foam cell size (inversely proportional to the surface area per unit volume). Strength is controlled by a combination of crosslink density and foam density, which can be expressed by crosslink density per unit volume, as defined below. Also, the effect of the type of cross-linking agent and other components can be significant.
[0140]
Useful polymer foams here are relatively open-celled. Cells in such a substantially open cellular foam structure have a sufficiently large inter-cell opening or “window” to allow easy liquid movement within the foam structure from one cell to another. Have.
[0141]
These substantially open cellular foam structures will generally have a reticulated nature with individual cells defined by a plurality of interconnected three-dimensionally branched webs. The strands of polymeric material that make up these branched webs can be referred to as “struts”. For the purposes of the present invention, foam material is “open cellular” if at least 80% of the cells in the foam structure are at least 1 μm in size are in liquid communication with at least one adjacent cell.
[0142]
In addition to being open-celled, these polymer foams are sufficiently hydrophilic to allow the foam to absorb aqueous liquids. The inner surface of the foam structure is rendered hydrophilic by residual hydrophilizing surfactants and / or salts left in the foam structure after polymerization, as described below, or by selected post-polymerization foam processing methods. The
[0143]
The degree to which these polymer foams are “hydrophilic” can be quantified by the “adhesion tension” value shown when in contact with the absorbent test solution. The adhesion tension exhibited by these foams can be measured experimentally using a method that measures the uptake weight of a test fluid, such as synthetic urine, for a sample having a known size and capillary suction specific surface area. . Such a method is described in detail in the test method section of US Pat. No. 5,387,207 (Dyer et al.) Issued February 7, 1995, which is incorporated herein by reference as part of the present specification. Has been. Foams useful as the dispensing material of the present invention generally measure from about 15 to about 65 dynes / cm, more preferably from about 20 to about 65, measured by capillary suction uptake of synthetic urine having a surface tension of 65 ± 5 dynes / cm. It shows an adhesion tension value of 65 dynes / cm.
[0144]
An important feature of these foams is their glass transition temperature (Tg). Tg represents the midpoint of the transition between the glassy and rubbery state of the polymer. Foams with a Tg above the use temperature can be very strong, but can be very rigid and have a tendency to potentially break. Such foams also creep under stress and tend to have poor flexibility when used at temperatures below the polymer Tg. The desired combination of mechanical properties (particularly strength and flexibility) typically requires a fairly selective range of monomer types and levels to achieve these desired properties.
[0145]
For dispensing foams useful for the present invention, the Tg should be as low as possible so long as the foam has acceptable strength. Thus, the monomers are selected to provide the corresponding homopolymer with the lowest possible Tg.
[0146]
It may also be important to determine the shape of the glass transition region of the polymer, ie whether it is narrow or wide as a function of temperature. The shape of this glass transition region is particularly important when the temperature (usually ambient or body temperature) during use of the polymer is at or near Tg. For example, a wide transition region means that the transition is incomplete at the temperature in use. Typically, if the transition is incomplete at the temperature in use, the polymer will exhibit greater stiffness and less flexibility. Conversely, if the transition is complete at the in-use temperature, then the polymer will show a faster recovery from compression. Therefore, it is desirable to control the Tg of the polymer and the width of the transition region to achieve the desired mechanical properties. In general, it is preferred that the Tg of the polymer be at least about 10 ° C. below the temperature during use. (Tg and width of transition region are the losses from dynamic mechanical analysis (DMA) measurements as described in US Pat. No. 5,563,179 (Stone et al.) Issued Oct. 8, 1996). Derived from tangent vs. temperature curve).
[0147]
Polymer foams useful for the present invention can be described by a number of parameters.
[0148]
Foams useful for the present invention are capable of wicking aqueous liquids up to a significant height with respect to gravity, eg, at least about 15 cm, by capillary action. The liquid column retained in the foam exerts a significant contractile capillary pressure. The foam will collapse at a height that is determined by both the strength of the foam (in compression) and the surface area per unit volume of the foam. This height is the capillary collapse pressure (CCP) expressed in cm when 50% of the foam volume at zero head pressure is lost. Preferred dispensing foams useful for the present invention will have a CCP of at least about 15 cm, more preferably at least about 20 cm, and even more preferably at least about 25 cm. Typically, preferred dispensing foams will have a capillary collapse pressure of about 15 cm to about 50 cm, more preferably about 20 cm to about 45 cm, and even more preferably about 25 to about 40 cm.
[0149]
One feature that may be useful when defining the preferred polymer foam is the cell structure. Foam cells, particularly cells formed by polymerizing a monomer-containing oil phase surrounding a relatively monomer-free aqueous phase droplet, are often substantially spherical in shape. These spherical cells are in communication with each other by openings (hereinafter referred to as holes between the cells). Both the size or “diameter” of the spherical cells and the diameter of the openings (holes) between the cells are commonly used to characterize the foam. Since the cells and the holes between the cells will not necessarily be approximately the same size in certain polymer foam samples, the average size of the cells and holes, i.e. the average diameter of the cells and holes, is often specified.
[0150]
Cell and hole size are parameters that can significantly affect many important mechanical characteristics and performance of foam materials, including the liquid wicking properties of these foams and the capillary pressure generated within the foam structure. Many methods are available to measure the average size of foam cells and holes. Useful methods include simple measurements based on scanning electron micrographs of foam samples. Foams useful as aqueous liquid absorbers according to the present invention preferably have a number average cell size of about 20 μm to about 60 μm, and typically about 30 μm to about 50 μm, and about 5 μm to about 15 μm, and typical Will have a number average hole size of about 8 μm to about 12 μm.
[0151]
“Capillary suction specific surface area” is a measure of the surface area of a polymer network that can be contacted with a test solution that is accessible to the test solution. Capillary suction specific surface area is measured by both cell unit size and polymer density in the foam, so that the amount of solid surface provided by the foam network is quantified to the extent such surface is involved in absorbency. is there.
[0152]
For purposes of the present invention, the capillary suction specific surface area is determined by measuring the amount of capillary uptake of a low surface tension liquid (eg, ethanol) generated in a foam sample of known mass and size. A detailed description of such a method for determining the foam specific surface area by capillary suction is described in the Test Methods section of the above-mentioned US Pat. No. 5,387,207. Any reasonable alternative for determining the capillary suction specific surface area can also be utilized.
[0153]
The dispensing foam useful for the present invention is preferably at least about 0.01 m.²/ Ml, more preferably at least about 0.03 m²It will have a capillary suction specific surface area of / ml. Typically, the capillary suction specific surface area is about 0.01 to about 0.20 m.²/ Ml, preferably about 0.03 to about 0.10 m²/ Ml, most preferably from about 0.04 to about 0.08 m²/ Ml.
[0154]
“Foam density” (ie foam weight per cubic centimeter of foam volume in air (g)) is specified here on an anhydrous basis. Foam density, as well as capillary suction specific surface area, can have a large impact on the numerous performance and mechanical characteristics of absorbent foam. These include absorption capacity for aqueous liquids and compression deflection characteristics. Foam density will vary with the state of the foam. The foam in the collapsed state clearly has a higher density than the same foam in the fully expanded state. Generally, the collapsed foam useful for the present invention is about 0.11 g / cm.^ThreeHaving a dry density of
[0155]
Any suitable gravimetric method that provides a measure of the mass of solid foam material per unit volume of foam structure can be used to measure foam density. For example, the ASTM gravimetric method fully described in the Test Methods section of US Pat. No. 5,387,207 above is one method that can be used for density measurements. Foam density is related to the weight per unit volume of the washed foam without any emulsifiers, fillers, surface treatment agents such as salts and the like. The foam useful for the present invention is preferably about 8 mg / cm.^Three~ About 77mg / cm^ThreeMore preferably about 11 mg / cm^Three~ 63mg / cm^ThreeEven more preferably about 13 mg / cm^Three~ 48mg / cm^ThreeWould have a dry density of
[0156]
Foams useful for the present invention can be obtained by polymerizing a particular type of W / O (water-in-oil) emulsion or HIPE having a fairly small amount of oil phase and a substantial amount of water phase. This process comprises the following steps:
A) Step of forming a W / O type emulsion from the following raw materials under specific temperature and specific shear mixing:
1) Oil phase containing:
a) from about 85 to about 98% monomer component by weight capable of forming a copolymer having a Tg of about 35 ° C. or less, the monomer component comprising:
i) from about 30 to about 80% by weight of at least one substantially water-insoluble monofunctional monomer capable of forming an amorphous atactic polymer having a Tg of about 25 ° C. or less;
ii) from about 5 to about 40% by weight of at least one substantially water insoluble monofunctional comonomer capable of imparting approximately equivalent toughness to that provided by styrene;
iii) divinylbenzenes, trivinylbenzenes, divinyltoluenes, divinylxylenes, divinylnaphthalenes, divinylalkylbenzenes, divinylphenanthrenes, divinylbiphenyls, divinyldiphenyl-methanes, divinylbenzyls, divinylphenyl ethers, From about 5 to about 30% by weight of a first multifunctional cross-linker substantially selected from divinyl diphenyl sulfides, divinyl furans, divinyl sulfide, divinyl sulfone, and mixtures thereof; and
iv) from about 0 to about 15% of a substantially water insoluble second multifunctional crosslinker selected from polyfunctional acrylates, methacrylates, acrylamides, methacryl-amides, and mixtures thereof. ;as well as
b) about 2 to about 15% by weight of an emulsifier component that is soluble in the oil phase and suitable to form a more stable W / O emulsion, the emulsifier component comprising: : (I) linear unsaturation C₁₆-C_{twenty two}Diglycerol monoesters of fatty acids, branch C₁₆-C_{twenty four}Diglycerol monoesters of fatty acids, branch C₁₆-C_{twenty four}Diglycerol monoaliphatic esters of alcohol, linear unsaturated C₁₆-C_{twenty two}Diglycerol monoaliphatic esters of higher alcohols, linear saturated C₁₂-C₁₄Diglycerol monoaliphatic esters of alcohol, linear unsaturated C₁₆-C_{twenty two}Fatty acid sorbitan monoesters, branched C₁₆-C_{twenty four}A first emulsifier having at least about 40% by weight of an emulsifying component selected from sorbitan monoesters of fatty acids and mixtures thereof; or (ii) a first emulsifier having at least 20% by weight of these emulsifying components A combination of a second emulsifier in a weight ratio of first to second emulsifier of about 50: 1 to about 1: 4; and
2) an aqueous phase comprising an aqueous solution containing: (i) about 0.2 to about 20% by weight of a water-soluble electrolyte; and (ii) an effective amount of a polymerization initiator;
3) a water relative oil phase ratio of about 12: 1 to about 125: 1 by volume: weight ratio; and
B) polymerizing the monomer component in the oil phase in the W / O emulsion to form a polymer foam material; and
C) Optionally, dehydrating the polymer foam.
[0157]
This process allows the formation of these absorbent foams that can dispense liquids as a result of having carefully balanced properties as described herein. These properties are achieved by careful selection of the type and level of crosslinkers and monomers, and emulsion formation parameters, especially the amount of shear mixing, temperature and water to oil ratio, these characteristics as the final density of the dry foam. appear.
[0158]
Polymer foams useful for the present invention can be prepared by polymerization of certain W / O type emulsions having a fairly high water relative oil phase ratio, which emulsions are generally known in the art as “HIPEs”. It has been. The polymer foam material resulting from the polymerization of such an emulsion is referred to below as “HIPE foam”. A detailed description of the general preparation of such HIPEs is given in the aforementioned US Pat. No. 5,563,179 and US Pat. No. 5,387,207.
[0159]
The relative amounts of water and oil phases used to form HIPEs are important in determining the structural, mechanical and performance properties of the resulting polymer foam, among many other parameters. In particular, the water-to-oil ratio (“W: O ratio”) in the emulsion varies inversely with the density of the final foam and has a significant effect on the cell size and capillary suction specific surface area of the foam and the dimensions of the struts forming the foam. May affect. Emulsions used to prepare HIPE foams useful in the present invention generally have an aqueous phase: oil phase of about 12: 1 to about 125: 1, and most typically about 15: 1 to about 90: 1. Will have a volume to weight ratio of Particularly preferred foams can be made from HIPEs having a ratio of about 20: 1 to about 75: 1.
[0160]
The major portion of the oil phase of HIPEs will contain monomers, comonomers and crosslinkers, as described, for example, in the above-mentioned US Pat. No. 5,387,207. It is important that these monomers, comonomers, and crosslinkers are substantially insoluble in water so that they are primarily soluble in the oil phase and not in the aqueous phase. The use of such substantially water-insoluble monomers ensures that HIPEs with the appropriate characteristics and stability are achieved. Of course, it is highly likely that the monomers, comonomers and crosslinkers used herein are of a type such that the resulting polymer foam is suitably non-toxic and suitably chemically stable. Is preferable. These monomers, comonomers and crosslinkers should preferably have little or no toxicity when present at very low residual concentrations during post-polymerization foam processing and / or use.
[0161]
Another important component of the oil phase is an emulsifier component that allows the formation of stable HIPEs. The emulsifier component comprises a first emulsifier and optionally a second emulsifier, for example as described in US Pat. No. 5,387,207 above.
[0162]
The oil phase used to form HIPEs comprises from about 85 to about 98% monomer component by weight and from about 2 to about 15% emulsifier component by weight. Preferably, the oil phase comprises from about 90 to about 98% monomer component by weight and from about 3 to about 10% emulsifier component by weight. The oil phase may also contain other optional components. One such optional component is well known to those skilled in the art, for example as described in US Pat. No. 5,290,820 (Bass et al.) Issued March 1, 1994, which is incorporated herein by reference. These are general types of oil-soluble polymerization initiators. Another preferred optional component is an antioxidant such as interference amine light stabilizers (HALS) and interference phenol stabilizers (HPS) or other antioxidants that are compatible with the initiator system used. Other optional components include plasticizers, fillers, colorants, chain transfer agents, dissolved polymers, and others.
[0163]
The discontinuous aqueous phase of HIPE is generally an aqueous solution containing one or more dissolved components, as described, for example, in the aforementioned US Pat. No. 5,387,207. One important dissolving component of the aqueous phase is a water-soluble electrolyte. The dissolved electrolyte minimizes the tendency of monomers, comonomers and crosslinkers that are primarily oil soluble to dissolve in the aqueous phase.
[0164]
This is believed to minimize the extent to which the polymeric material fills the cell window at the oil / water interface, which in turn is formed by aqueous phase droplets during polymerization. Accordingly, the presence of electrolyte and the resulting ionic strength of the resulting aqueous phase is believed to determine whether and to what extent the resulting preferred polymer foam can be open-celled.
[0165]
HIPEs will also typically contain a polymerization initiator. Such initiator components are typically added to the aqueous phase of HIPEs and may be any of the conventional water soluble free radical initiators. These include peroxy compounds such as sodium persulfate, potassium and ammonium, hydrogen peroxide, sodium peracetate, sodium percarbonate and others. Conventional redox initiator systems can also be used. Such a system is formed by combining the above peroxide compound with a reducing agent such as sodium sulfite, L-ascorbic acid or iron salt.
[0166]
The initiator can be present up to about 20 mole percent based on the total moles of polymerizable monomers present in the oil phase. More preferably, the initiator is present in an amount of about 0.001 to about 10 mole percent, based on the total moles of polymerizable monomers present in the oil phase.
[0167]
The polymer for forming the HIPE foam structure will preferably be substantially free of polar functional groups. This means that the polymer foam is relatively hydrophobic in nature. These hydrophobic foams can find utility when absorption of hydrophobic liquids is desired. This type of use includes uses where it is desirable for the oily component to be mixed with water and separated and sequestered, such as in the case of an oil spill at sea.
[0168]
When these foams are used as aqueous fluids to be cleaned, such as spilled juice or milk, and / or bodily fluid absorbers such as urine, they generally make the foam relatively more hydrophilic. For further processing. If necessary, hydrophilization of the foam can be accomplished by treating the HIPE foam with a hydrophilizing surfactant in the manner described in US Pat. No. 5,387,207.
[0169]
These hydrophilizing surfactants can be any material that enhances the water wettability of the polymer foam surface. They are well known in the art and can include various surfactants, preferably of non-ionic type, as described in US Pat. No. 5,387,207.
[0170]
Another material typically incorporated into the HIPE foam structure is a water-soluble inorganic salt that is hydratable and more preferably hygroscopic or meltable. Such salts include, for example, toxicologically acceptable alkaline earth metal salts. This type of salts and their use with oil-soluble surfactants as foam hydrophilizing surfactants are described in U.S. Pat. No. 5,352,711 (DesMarais). Preferred salts of this type include calcium halides such as calcium chloride which can also be used as aqueous phase electrolytes in HIPE as mentioned previously.
[0171]
Hydratable inorganic salts can be readily incorporated by treating the foam with an aqueous solution of such salts. These saline solutions can generally be used to treat the foam after completion of or as part of the process of removing the residual aqueous phase from the foam immediately after polymerization. Treatment of the foam with such a solution is preferably a residual amount in the range of at least about 0.1% by weight of the foam, typically in the range of about 0.1 to about 12%, such as water such as calcium chloride. Deposit compatible inorganic salts.
[0172]
Treatment of these relatively hydrophobic foams with a hydrophilizing surfactant (with or without hydratable salts) typically to impart the appropriate hydrophilicity to the foam. Will be implemented to the extent necessary. However, some foams of the preferred HIPE type are suitably hydrophilic when prepared and also incorporate a sufficient amount of a hydratable salt therein, and thus a hydrophilizing surfactant or No additional treatment with hydratable salts is required. In particular, such preferred HIPE foams include those previously described when certain oil phase emulsifiers and calcium chloride are used in the HIPE. In those cases, the inner surface of the polymerized foam will be suitably hydrophilic and contain or deposit a sufficient amount of calcium chloride even after the polymer foam has been dehydrated to a practical extent. It will contain residual aqueous phase liquid.
[0173]
The foam preparation process typically includes the following steps: 1) forming a stable high internal phase emulsion (HIPE); 2) suitable for forming this stable emulsion into a solid polymer foam structure. Polymerizing / curing step under conditions; 3) optionally washing the solid polymer foam structure to remove the initial residual aqueous phase from the polymer foam structure and, if necessary, any necessary hydrophilization Treating the polymer foam structure with a hydrophilizing surfactant and / or a hydratable salt to deposit a surfactant / hydratable salt; and 4) thereafter the polymer foam Dehydrating the structure. This method is more fully described in the aforementioned US Pat. No. 5,387,207.
[0174]
In order to use each material in the absorbent structure, these materials can be combined with other elements to create a fluid treatment member comprising the materials according to the description listed above.
[0175]
<Requirements for storage absorbent member>
As explained above, the dispensing member exhibits a certain release characteristic, but this must be adapted to the absorbent characteristics of the absorbent storage member or material.
[0176]
Thus, a storage absorbent member compatible with the present invention exhibits a high capillary suction capacity. For purposes of the present invention, this high suction capacity is measured by the ability to take up fluid at a constant capillary height that is commonly encountered when the member is placed in an absorbent body. The capillary adsorption / absorption capacity test (hereinafter also referred to as “capsorption test”) is the amount of test liquid per gram of absorbent storage member that is absorbed when the storage member is placed at various heights on the capillary adsorption device. Measure. The capillary absorption capacity test is described in more detail in the test method section below.
[0177]
In certain embodiments, a high capillary suction capacity storage absorbent member suitable for the present invention is at least about 15 g / g, preferably at least about 18 g / g, more preferably at least about 20 g / g, more preferably 35 cm high. Has a capillary adsorption capacity (CSAC) of at least about 22 g / g. Typically, these storage absorbent members are about 15 g / g to about 60 g / g, more typically about 18 g / g to about 50 g / g, and even more typically about 20 g / g at a height of 35 cm. It will have a capillary adsorption capacity of g to about 40 g / g.
[0178]
In yet another embodiment, the high capillary suction capacity storage absorbent member is at least about 8 g / g, preferably at least about 11 g / g, more preferably at least about 15 g / g, even more preferably at least about 19 g at a height of 50 cm. / G CSAC. Typically, these storage absorbent members are about 8 g / g to about 40 g / g, more typically about 11 g / g to about 35 g / g, and more typically about 15 g / g at a height of 50 cm. It will have a CSAC of g to about 30 g / g.
[0179]
In yet another embodiment, the high capillary suction capacity storage absorbent member is at least about 6 g / g, preferably at least about 9 g / g, more preferably at least about 12 g / g, and even more preferably at least about 15 g at a height of 80 cm. / G CSAC. Typically, these storage absorbent members are about 6 g / g to about 35 g / g, more typically about 9 g / g to about 30 g / g, more typically about 12 g / g at a height of 80 cm. It will have a CSAC of g to about 25 g / g.
[0180]
In yet another embodiment, the high capillary suction capacity storage absorbent member is at least about 5 g / g, preferably at least about 7 g / g, more preferably at least about 10 g / g, even more preferably at least at a height of 100 cm. It has a CSAC of about 14 g / g. Typically, these storage absorbent members are from about 5 g / g to about 30 g / g, more typically from about 7 g / g to about 25 g / g, more typically about 10 g / g at a height of 100 cm. It will have a CSAC of ~ 20 g / g.
[0181]
Although not a requirement, a particularly preferred storage absorbent member has an initial effective uptake rate of 200 cm at least about 3 g / g / hr, more preferably at least about 4 g / g / hr, and most preferably at least about 8 g / g / hr. Will. Typically, the effective uptake rate at 200 cm is about 3 to about 15 g / g / hr, more typically about 4 to about 12 g / g / hr, more typically about 8 to about 12 g / g. / Hr.
[0182]
Although the minimum capillary suction capacity described above is important for the storage and absorbent members of the present invention, these members are more preferably (but not necessarily) at least about 15 g at zero head pressure (ie, at 0 cm in the capsorption test). It will have a capillary adsorption capacity of / g. In another preferred embodiment, the storage absorbent member will now exhibit the required g / g uptake at the at least two suction heights described above. Thus, for example, a preferred storage absorbent member will have two or more of the following properties: (i) at a height of 35 cm, at least about 10 g / g, preferably at least about 13 g / g, more preferably at least about 20 g / g. Even more preferably at least about 22 g / g capillary adsorption capacity (CSAC); (ii) at least about 8 g / g at a height of 50 cm, preferably at least about 11 g / g, more preferably at least about 15 g / g; Even more preferably at least about 19 g / g CSAC; (iii) 80 cm height at least about 6 g / g, preferably at least about 9 g / g, more preferably at least about 12 g / g, even more preferably at least about 15 g (Iv) at least about 5 g / g at a height of 100 cm, preferably at least about A CSAC of 7 g / g, more preferably at least about 10 g / g, even more preferably at least about 14 g / g.
[0183]
Yet another way to describe a storage absorbent member that is suitable for the present invention is that a high capillary suction capacity storage absorbent member requires a high intermediate absorption pressure. The intermediate absorption pressure of a material is defined as the pressure at which the material has a capillary absorption efficiency of 50%, and the material absorbs the maximum absorption capacity in the capillary absorption test described in the Test Methods section. Is measured by determining a height called CSAH50.
[0184]
Preferred storage absorbent members suitable for the present invention are at least about 15 g / g at a height of 0 cm, preferably at least about 20 g / g, more preferably at least about 25 g / g, and most preferably at least about 35 g / g. A high capillary suction capacity storage and absorption member having an intermediate capillary absorption height CSAH50 of at least 35 cm, preferably at least 45 cm, more preferably at least 60 cm, and most preferably at least 80 cm.
[0185]
<Material for achieving the requirements for storage and absorption members>
<High surface area material>
Storage absorbent members useful for the present invention preferably comprise high surface area materials. It is this high surface area material that provides a member with high capillary adsorption capacity, either by itself or in combination with other elements such as hydrogel-forming absorbent polymers. As discussed herein, for at least one high surface area material, their capillary adsorption capacity (if present in the member, hydrogel-forming polymer or other actual absorptive properties such as adhesives, binders, etc. Measured without including any other material included in the member). It is recognized that materials with high surface areas may have uptake capabilities at very high suction heights (eg, 100 cm or more). This allows the high surface area material to provide one or both of the following functions: i) a capillary pathway from the liquid to an absorbent, such as an osmotic absorbent, and / or ii) additional adsorption capacity. Thus, although high surface area materials can be described by their surface area per weight or volume, the applicant here uses capillary adsorption capacity instead to describe high surface area material, which is generally This is because the performance parameter provides the suction capacity necessary for providing the improved absorbent to the absorbent member of the present invention. It is recognized that certain high surface area materials such as glass microfibers by themselves will not exhibit high capillary adsorption capacity at virtually any height, especially at very high heights (eg, 100 cm and above). Will be done. Nonetheless, such materials may provide a desirable capillary pathway for liquids in hydrogel-forming absorbent polymers or other absorbents to provide the necessary capillary adsorption capacity even at fairly high heights.
[0186]
Any material having a sufficient capillary absorption capacity will be useful in the storage absorbent member of the present invention. In this context, the term “high surface area material” is itself (ie, measured without including any other material making up the osmotic absorbent or storage absorbent member) one or more of the following: Means any material exhibiting capillary adsorption capacity: (I) at least about 2 g / g at a suction height of 100 cm, preferably at least about 3 g / g, even more preferably at least about 4 g / g, and even more preferably Capillary adsorption / absorption capacity of at least about 6 g / g at a height of 100 cm; (II) at least about 5 g / g, preferably at least about 8 g / g, more preferably at least about 12 g / g at a height of 35 cm. Capillary adsorption capacity; (III) at least about 4 g / g, preferably at least about 7 g / g, more preferably at least about 9 g / g of hair at a height of 50 cm Adsorption capacity; (IV) Capillary adsorption capacity at least about 1 g / g, preferably at least about 2 g / g, more preferably at least about 3 g / g, even more preferably at least about 5 g / g at a height of 140 cm Or (V) a capillary adsorption capacity of at least about 1 g / g, preferably at least about 2 g / g, more preferably at least about 3 g / g, even more preferably at least about 5 g / g at a height of 200 cm.
[0187]
In certain embodiments, the high surface area material has properties such that it can provide a fibrous web or fibrous matrix when combined with other absorbents or other osmotic absorbents, such as hydrogel-forming absorbent polymers. It will be fibrous (hereinafter referred to as “high surface area fibers”). Alternatively, in a particularly preferred embodiment, the high surface area material will be an open cell hydrophilic polymer foam (hereinafter referred to as “high surface area polymer foam” or more commonly “polymer foam”). These materials are described in detail below.
[0188]
<High surface area fiber>
High surface area fibers useful in the present invention include naturally occurring (modified or unmodified) fibers as well as synthetically produced fibers. High surface area fibers have a much larger surface area than fibers typically used in absorbent bodies such as wood pulp fibers. The high surface area fibers used in the present invention will desirably be hydrophilic. As used herein, the term “hydrophilic” describes a fiber or surface of a fiber that is wettable by an aqueous liquid (eg, aqueous body fluid) deposited on these fibers. Hydrophilicity and wettability are typically defined by the contact angle and surface tension of the liquid and the contained solid. This is Robert F. It is discussed in detail in an American Chemical Society (ACS) publication entitled “Contact Angle, Wettability and Adhesion” compiled by Gould. The fiber, or the surface of the fiber, usually coexists in both states, but the contact angle between the liquid and the fiber or its surface is less than 90 °, or the liquid tends to spread naturally across the surface of the fiber. It is said to be wetted (ie, hydrophilic) by the liquid at either time. In contrast, a fiber or surface is considered hydrophobic when the contact angle is 90 ° or greater and the liquid does not spread naturally across the surface of the fiber. The hydrophilic nature of the fibers useful herein may be inherent in the fibers, or they may be natural hydrophobic fibers that have been treated to make them hydrophilic. Materials and methods for providing hydrophilic properties to native hydrophobic fibers are well known.
[0189]
High surface area fibers useful herein will have a capillary suction non-surface area in the same range as the polymer foam described below. However, typically high surface area fibers are characterized by the well-known BET surface area.
[0190]
High surface area fibers useful herein include, for example, glass ultrafine fibers such as glass wool available from Evanite Fiber Corp. (Corvallis, Oregon). Glass ultrafine fibers useful herein will typically have a fiber diameter of less than about 0.8 μm, more typically from about 0.1 μm to about 0.7 μm. These ultrafine fibers are at least about 2 m²/ G, preferably at least about 3 m²/ G surface area. Typically, the surface area of the glass microfiber is about 2 m.²/ G to about 15m²/ G. Exemplary glass microfibers for use herein are those available from Evanite Fiber Corporation, such as 104-type glass fibers having a nominal fiber diameter of about 0.5 μm. These glass ultrafine fibers are about 3.1m²/ G calculated surface area.
[0191]
Another type of high surface area fiber useful herein is fibrillated cellulose acetate fiber. These fibers (hereinafter referred to as “fibrets”) have a high surface area compared to cellulose-derived fibers commonly used in absorbent technology. Such fibrets have very small diameter regions such that their particle size width is typically about 0.5 to about 5 μm. These fibrets are typically about 20m²/ G total surface area. A representative fibrette useful herein as a high surface area material is available from Hoechst Celanese Cop. (Charlotte, NC) as cellulose acetate Fiberts®. For a detailed discussion of fibrettes, including their physical properties and methods for their preparation, see “Cellulose Acetate Fibrettes: Fibrilization with High Surface Areas,” the disclosure of each of which is incorporated herein by reference. Pulp (Cellulose Acetate Fibrets: A Fibrillated Pulp With High Surface Area) ", Smith, JE, Tappi Journal, Dec. 1988, p.237; and US Pat. No. 5,486,410 issued Jan. 23, 1996. See issue (Groeger et al.).
[0192]
In addition to these fibers, those skilled in the art will recognize that other fibers well known in the absorbent art can be modified to provide high surface area fibers for use herein. Exemplary fibers that can be modified to achieve the high surface area required by the present invention are disclosed in the aforementioned US Pat. No. 5,599,335 (see especially columns 21-24).
[0193]
Regardless of the nature of the high surface area fibers utilized, the fibers and other absorbent materials, such as, for example, osmotic absorbents, will be separate materials before being combined. As used herein, the term “separate” means that the high surface area fibers and other absorbents are each formed before being combined to form a storage absorbent member. In other words, the high surface area fibers are not formed subsequent to mixing with other absorbents, nor are the other absorbents formed after bonding with the high surface area fibers. The bonding of each separate component ensures that the high surface area fibers have the desired morphology, and more importantly, the desired surface area.
[0194]
<High surface area polymer foam>
The high surface area polymer foams useful herein are described below with respect to some of their physical properties. In order to measure these certain properties, it is necessary to perform an analysis on the foam at the sheet diameter. Thus, the foam is used in particulate form, but as long as it is prepared from a preformed sheet, physical property measurements can be performed on the sheet foam (ie before forming the particles). I will. If the foam is formed into particles (or beads) in situ during the polymerization process, a similar foam (with respect to chemical composition, cell size, W: O ratio, etc.) is formed into a sheet for the purpose of making such measurements. be able to.
[0195]
High surface area polymer foams useful in the high capillary suction storage and absorbent members of the present invention are known in the art. Particularly preferred foams are those obtained by polymerizing high internal phase W / O type emulsions as described, for example, in US Pat. No. 5,387,207 and US Pat. No. 5,650,222. is there. Another particularly preferred polymer foam was filed on Mar. 1998 by T. DesMarais et al. Entitled “HIGH SUCTION POLYMERIC FOAM MATERIALS”, the disclosure of which is incorporated herein by reference. Filed on Mar. 1998 by T. DesMarais et al. Entitled “Absorptive Materials for Dispersing AQUEOUS LIQUIDS” and US Patent Application No. (P & G Case) and other co-pending applications. US Patent Application No. (P & G case), which is a co-pending application. (Particularly preferred foams described in one or both of these co-pending applications are described in the Examples section below) The polymer foams useful here are substantially open-celled. This means that many of the individual cells of the form are in uninterrupted communication with neighboring cells. Cells in such a substantially open cell foam structure have inter-cell openings or “windows” that are large enough to allow easy liquid transfer within the foam structure from one cell to another. .
[0196]
These substantially open cell foam structures generally have a reticulated feature with individual cells defined by a plurality of interconnected three-dimensionally branched webs. The strands of polymer material that make up these branched webs can be referred to as “struts”. For the purposes of the present invention, the most preferred foam material will have at least about 80% cells that are at least 1 μm in size in liquid communication with at least one adjacent cell in the foam structure.
[0197]
In addition to being open-celled, these polymer foams are sufficiently hydrophilic to allow the foam to absorb aqueous liquids. The inner surface of the foam structure is rendered hydrophilic by residual hydrophilizing surfactant left in the foam structure after polymerization, as described below, or by selected post-polymerization foam processing methods.
[0198]
The degree to which these polymer foams are “hydrophilic” can be quantified by the “adhesion tension” value shown when in contact with the absorbent test solution. The adhesion tension exhibited by these foams can be measured experimentally using a method that measures the uptake weight of a test fluid, such as synthetic urine, for samples having known dimensions and capillary suction specific surface areas. Such a method is described in detail in the test method section of US Pat. No. 5,387,207, which is incorporated herein by reference. Foams useful as high surface area materials in the present invention generally measure from about 15 to about 65 dynes / cm, more preferably from about 20 to about 60 measured by capillary suction uptake of synthetic urine having a surface tension of 65 ± 5 dynes / cm. It exhibits an adhesion tension value of about 65 dynes / cm.
[0199]
Polymer foams useful herein can be prepared preferably in a collapsed (ie, unexpanded) form, the polymer foam absorbs such liquid when contacted with an aqueous liquid, and the amount absorbed is capillary pressure. When the bonding pressure obtained by adding a sealing pressure is lowered below the expansion pressure of the foam (explained below), it expands. These collapsed polymer foams are typically obtained by squeezing the aqueous phase from the polymerized HIPE foam through compressive force and / or by thermal drying and / or vacuum dehydration. After compression and / or after heat drying and / or vacuum dehydration, the polymer foam is in a collapsed or unexpanded state.
[0200]
A typical collapsed HIPE foam cell structure from which water is squeezed out by compression is shown in the photomicrographs of FIGS. 3 and 4 of the aforementioned US Pat. No. 5,650,222. As can be seen from these figures, the cellular structure of the foam is distorted particularly when compared to the expanded HIPE foam structure shown in FIGS. 1 and 2 of the '222 patent. Similarly, as is apparent from FIGS. 3 and 4 of the '222 patent, the voids or pores (dark areas) in the collapsed foam structure are flattened or elongated. (It is noted that the foam depicted in the '222 patent is sheet-shaped; as explained below, sheet-shaped foam is useful here, but in certain preferred embodiments, the foam is particulate. The cell structure of another useful HIPE-derived foam (in its expanded state) is depicted here in FIGS. 3 and 4. The preparation of this particular foam and related foams is described herein in Examples 2-4, and these ultra high surface area foams are further described in the “High Suction Polymer Foam Material (HIGH SUCTION)” incorporated herein by reference in their respective disclosures. US Patent Application No. (P & G Case) filed on March 1998, by TADesMarais et al. Entitled “POLYMERIC FOAM MATERIALS” and “ABSORBENT MATERIALS FOR DISTRIBUTING AQUEOUS LIQUIDS) is described in more detail in co-pending US Patent Application No. (P & G) filed March 1998 by TADesMarais et al.
[0201]
Following compression and / or heat drying / vacuum dehydration, the collapsed polymer foam can re-expand when infiltrated with an aqueous liquid. Surprisingly, these polymer foams remain in this collapsed or unexpanded state for a significant period of time, for example up to at least about one year. The ability of these polymer foams to remain in this collapsed / unexpanded state is believed to be due to capillary forces and particularly the capillary pressure generated within the foam structure. As used herein, “capillary pressure” means the pressure differential across the liquid / air interface due to a semi-circular curvature within a narrow range of pores in the foam. [See Chatterjee, “Absorbency” Textile Scienc and Technology, Vol. 7, 1985, p. 36]
After compression and / or heat drying / vacuum dehydration to a practical extent, these polymer foams were absorbed into the water of hydration associated with the hygroscopic hydrate salts incorporated therein, as well as into the foam. Has residual water, including both free water. This residual water (assisted by hydrated salt) is thought to exert capillary pressure on the resulting collapsed foam structure. The collapsed polymer foam of the present invention is at least about 4% by weight of the foam when stored at ambient conditions of 72 ° F. (22 ° C.) and 50% relative humidity, typically about 4 to about 40%. May have a residual water content of Preferred collapsed polymer foams have a residual water content of at least about 5 to about 30% by weight of the foam.
[0202]
An important parameter for these foams is their glass transition temperature. Tg represents the midpoint of the transition between the glassy and rubbery state of the polymer. Foams having a Tg higher than the service temperature can be very strong, but can also be rigid and potentially prone to failure. Such foams also typically take longer to return to the expanded state when stored in a collapsed state for a longer period of time and then wet with an aqueous solution that is cooler than the Tg of the polymer. Particularly desirable combinations of mechanical properties of strength and flexibility typically require a considerable selective range of monomer types and levels to achieve these desired properties.
[0203]
For foams useful for the present invention, the Tg should be as low as possible so long as the foam has an acceptable strength at the temperatures in use. Thus, the monomers are selected to provide the corresponding homopolymer with the lowest possible Tg. It has been discovered that the chain length of alkyl groups on acrylate and methacrylate comonomers can be longer than expected from the Tg of the homologous homopolymer series. Specifically, it has been discovered that homologous series of alkyl acrylate or alkyl methacrylate homopolymers have a minimum Tg with a chain length of 8 carbon atoms. In contrast, the minimum Tg of the copolymers of the present invention occurs with a chain length of about 12 carbon atoms. (Alkyl-substituted styrene monomers can be used in place of alkyl acrylates and methacrylates, but their availability is currently greatly limited.)
It may also be important for the shape of the glass transition region of the polymer, ie whether it is narrow or wide as a function of temperature. This glass transition region shape is important especially when the polymer in-use temperature (usually ambient or body temperature) is at or near Tg. For example, a wide transition region means that the transition is incomplete at the temperature during use. Typically, if the transition is incomplete at temperature during use, the polymer will exhibit greater stiffness and less flexibility. Conversely, if the transition is complete at the temperature in use, then the polymer will show a faster recovery from compression when wetted with an aqueous solution. Therefore, it is desirable to control the Tg of the polymer and the width of the transition region to achieve the desired mechanical properties. In general, the Tg of the polymer is preferably at least 10 ° C. below the temperature during use. (Tg and transition region width are derived from loss tangent versus temperature curves from dynamic mechanical analysis (DMA) measurements as described in US Pat. No. 5,565,222).
[0204]
Although high surface area materials have generally been described by their capillary adsorption capacity, high surface area polymer foams useful here are also described by their capillary suction specific surface area (hereinafter referred to as “CSSSA”). be able to. In general, CSSSA is a measure of the test liquid accessible surface area of a polymer network that forms a particulate foam per unit mass of bulk foam material (polymer structural material plus solid residual material). Capillary suction specific surface area is determined by both the size of the cell units in the foam and the density of the polymer, and is therefore a method of quantifying the total amount of solid surface provided by the foam network to the extent that such area is related to absorbency. . To characterize the foam useful herein, CSSSA is measured on a sheet of the foam even when the foam is in particulate form when incorporated into a storage absorbent member.
[0205]
Foam CSSSA is particularly important if the foam provides the necessary capillary aspiration for use in preparing the storage absorbent member of the present invention. This is because the capillary pressure generated in the foam structure is proportional to the capillary suction specific surface area. In addition, CSSSA is important for whether proper capillary pressure is generated within the foam structure to maintain the collapsed state until infiltrated with aqueous liquid. Assuming that other factors such as foam density and adhesion tension are constant, this means that as CSSSA increases (or decreases), the capillary pressure within the foam structure also increases (or decreases) proportionally. Means.
[0206]
For the purposes of the present invention, CSSSA is determined by measuring the amount of capillary uptake of a low surface tension liquid (eg, ethanol) generated within a foam sample of known mass and size. A detailed description of such a method for determining foam specific surface area is provided in the Test Methods section of US Pat. No. 5,387,207, which is incorporated by reference. Any reasonable alternative for determining CSSSA can also be utilized.
[0207]
Disintegrated polymer foam useful as an absorbent for the present invention is at least about 3 m.²Will have a CSSSA of / g. Typically, CSSSA is about 3 to about 30 meters.²/ G, preferably about 4 to about 17 m²/ G, most preferably about 5 to about 15 m²/ G. Foams having such CSSSA values (about 0.010 to about 0.033 m²In general) will have a particularly desirable balance of absorption capacity, liquid retention and liquid wicking or dispersion properties for aqueous liquids such as urine. In addition, foams having such CSSSA can generate sufficient capillary pressure to maintain the foam in a collapsed, unexpanded state until infiltrated with such aqueous liquid.
[0208]
As noted above, for particularly preferred collapsible polymer foams, in their collapsed state, the capillary pressure generated within the foam structure is at least equal to the force exerted by the elastic recovery or module of the compressed polymer. In other words, the capillary pressure required to keep the collapsed foam fairly thin is measured by the counteracting force exerted by the compressed polymer foam when it attempts to “bounce”. The elastic recovery tendency of the polymer foam is maintained in this compressed state until the expanded foam is compressed to about 1/6 (17%) of its original expanded thickness and then the relaxation stress value is measured. It can be estimated from the stress-strain experiment. Alternatively, and for the purposes of the present invention, the relaxation stress value is estimated from measurements on a polymer foam that is in a collapsed state when contacted with an aqueous liquid such as water. This alternative relaxation stress value is hereinafter referred to as the “expansion pressure” of the foam. The expansion pressure for collapsed polymer foams of the present invention is about 50 kilopascals (kPa) or less and typically about 7 to about 40 kPa. A detailed description of the method for estimating the expansion pressure of the foam is given in the test method section of US Pat. No. 5,387,207.
[0209]
Another important property of high surface area polymer foams useful in the present invention is their free absorption capacity. “Free absorption capacity” (or “FAC”) is the total amount of test fluid (synthetic urine) that a certain foam sample absorbs in its cell structure per unit mass of solid material in the sample. To be particularly useful in the storage absorbent members of the present invention, the polymer foam should have a free absorption capacity of about 30 to about 100 ml, preferably about 30 to about 75 ml of synthetic urine per gram of dry foam material. Don't be. A method for measuring the free absorption capacity of a foam is described below in the test method section of US Pat. No. 5,650,222.
[0210]
Upon exposure to an aqueous liquid, the preferred collapsed polymer foam absorbs the liquid and expands. Polymer foams absorb more liquid than most other foams in their expanded state. The “expansion coefficient” for these foams is at least about 4 times, that is, the thickness of the foam in its expanded state is at least about 4 times the thickness of the foam in its collapsed state. The collapsed foam preferably has an expansion coefficient in the range of about 4 times to about 15 times, more preferably about 5 times to about 10 times.
[0211]
For the purposes of the present invention, the relationship between expanded and collapsed thickness for a foam that is compressed and dehydrated can be empirically predicted from the following equation:
Thickness (expanded) = thickness (collapsed) × ((0.133 × W: O ratio) ± 2)
Where: thickness (expanded) is the thickness of the foam in the expanded state;
Thickness (collapsed) is the thickness of the foam in the collapsed state;
And the W: O ratio is the water to oil ratio of HIPE from which the foam is made. Thus, a typical polymer foam made from an emulsion with a 60: 1 water to oil ratio will have a predicted expansion coefficient of 8.0, ie, the expanded thickness is that of the collapsed thickness of the foam. 8 times. A method for measuring the expansion coefficient is described below in the test method section of US Pat. No. 5,650,222.
[0212]
An important mechanical characteristic of high surface area polymer foams useful in the present invention is their strength in the expanded state as measured by resistance to compression deflection (RTCD). The RTCD indicated here by the foam is a function of the density and structure of the polymer module and the foam network. The polymer module is in turn measured by: a) the composition of the polymer; b) the conditions under which the foam is polymerized (eg, especially the completeness of polymerization obtained, especially with respect to cross-linking); and c) The degree to which the polymer is plasticized by residual materials such as emulsifiers that remain in the foam structure after processing.
[0213]
In order to be useful as the high surface area portion of the absorbent member of the present invention, the polymer foam must be appropriately resistant to deformation or compression due to forces encountered during use. Foams that do not have sufficient foam strength with respect to RTCD may provide the necessary capillary suction capacity under unloaded conditions, but are caused by the exercise and activity of the user of the absorbent containing the foam. Under compressive stress they will not provide their capacity.
[0214]
The RTCD exhibited by the polymer foam useful in the present invention can be quantified by measuring the amount of strain produced in a sample of saturated foam held under a constant sealing pressure for a specified temperature and duration. Methods for performing this particular type of test are described below in the Test Methods section of US Pat. No. 5,650,222. Foams useful herein are preferably sealed at 5.1 kPa, typically about about the foam structure, when saturated with synthetic urine having a surface tension of 65 ± 5 dynes / cm to its free absorption capacity. RTCDs that produce 90% or less strain will be shown. Preferably, the strain produced under such conditions is from about 1 to about 90%, more preferably from about 1 to about 25%, even better still from about 2 to about 10%, even more preferably from about 2 to about 5%. Will be in range.
[0215]
The high surface area polymer foams useful herein can also be described by their vertical suspended adsorption height (hereinafter referred to as “VHSH”). The VHSH height in X% is the height in cm when X% of the capacity (or FAC) at 0 cm is maintained in the foam. In principle, X can be any value, but an important typical value is VHSH at 90%. The most reproducible measure for VHSH is achieved with X = 90% within our experience. It will be apparent to those skilled in the art that this single point value does not adequately represent the shape of the curve obtained in the volume versus height plot. However, this single point serves as a practical comparison point for the forms useful here. In this regard, the foam typically has an equilibrium 90% VHSH of at least about 20 cm, preferably at least about 40 cm, more preferably at least about 60 cm, even more preferably at least about 70 cm, and even more preferably at least about 80 cm. Would have. Typically, preferred polymer foams are about 20 to about 90 cm, more typically about 60 to about 90 cm, even more typically about 70 to about 90 cm, even more typically about 80 to about 90 cm. Of 90% VHSH. The method for measuring 90% VHSH is described in detail in the Test Methods section below. As pointed out above, when the high surface area polymer foam is in particulate form, when combined with other absorbents such as, for example, osmotic absorbents, 90% VHSH is on the corresponding sheet-form foam. Measured (ie before forming the particles). If the foam is formed into particles (or beads) during the polymerization process, a similar foam can be formed into a sheet to assess the 90% VHSH of the foam.
[0216]
Foam cells, and especially cells formed by polymerizing a monomer-containing oil phase surrounding a substantially monomer-free aqueous phase droplet, will often be substantially spherical in shape. The size or “diameter” of such spherical cells is a parameter commonly used to characterize foams. Since the cells in a sample of a certain polymer foam are not necessarily approximately the same size, an average cell size, i.e., an average cell diameter, is often specified.
[0217]
A number of methods are available for measuring the average cell size of the foam. However, the most useful methods for measuring cell size in foams include simple measurements based on scanning electron micrographs of foam samples.
[0218]
The cell size measurements given here are based on the number average cell size of the foam in its expanded state, as shown, for example, in FIG. 1 of US Pat. No. 5,650,222. Foams useful in accordance with the present invention will preferably have a number average cell size of about 80 μm or less, and typically about 5 to about 50 μm.
[0219]
“Foam density” (ie grams of foam per cubic centimeter of foam volume in air) is specified here on an anhydrous basis. The amount of water soluble residual material absorbed, such as residual salts and liquid remaining in the foam after HIPE polymerization, washing and / or hydrophilization is ignored when calculating and displaying the foam density. However, the foam density includes other water insoluble residual materials such as emulsifiers present in the polymerized foam. Such residual material may actually contribute to a significant mass for the foam material.
[0220]
Any suitable gravimetric method that provides a measure of the mass of solid foam material per unit volume of foam structure can be used to measure foam density. For example, the ASTM gravimetric method fully described by the test method section of US Pat. No. 5,387,207 (Dyer et al.), Issued February 7, 1995, described above, can be used for density measurements. There are two ways. In their collapsed state, the polymer foam useful in the present invention is about 0.1 to about 0.2 g / cm.^Three, Preferably about 0.11 to about 0.19 g / cm^ThreeAnd most preferably from about 0.12 to about 0.17 g / cm^ThreeHaving an anhydrous base density value in the range of (excluding any residual salts and / or water). In their expanded state, the polymer foam useful herein is about 0.01 to about 0.033 g / cm.^Three, Preferably about 0.013 to about 0.033 g / cm^ThreeHaving an anhydrous base density value in the range of
[0221]
Vertical wicking, i.e., liquid wicking in the opposite direction of gravity, is a desirable performance attribute for the polymer foam useful herein. For the purposes of the present invention, the vertical wicking rate is a reflection of the permeability of the material, and thus the ability of the material to deliver liquid to other absorbents, such as hydrogel-forming absorbent polymers or other osmotic absorbents.
[0222]
The vertical wicking rate is measured by measuring the time required for a colored test solution (eg, synthetic urine) in the reservoir to wick a 5 cm vertical distance through a test strip of a particular size foam. The vertical wicking method is described in more detail in the test method section of US Pat. No. 5,387,207, but is performed at 31 ° C. instead of 37 ° C. To be particularly useful with absorbent members to absorb urine, foams useful herein will preferably wick synthetic urine to a height of 5 cm within about 15 minutes (65 + 5 dynes / cm). . More preferably, the preferred foam absorbent of the present invention wicks synthetic urine to a height of 5 cm within about 10 minutes.
[0223]
The vertical wicking absorption capacity test measures the amount of test fluid per gram of absorbent foam held within each 1 inch (2.54 cm) vertical section of the same standard size foam sample used in the vertical wicking test. To do. Such measurements are generally made after the test solution is wicked vertically until the sample equilibrates (eg, after about 18 hours). Similar to the vertical wicking test, the vertical wicking absorption capacity test is more fully described by the test method section of US Pat. No. 5,387,207 (Dyer et al.), Issued February 7, 1995, above. Yes. A high vertical wicking absorption capacity at high height is theoretically equivalent to a high capillary absorption capacity at high height. Since the sheet form of the foam useful here is sensitive to previous tests, which are easier and cheaper to perform, the means of characterizing this important parameter of the foam of the present invention is from previous tests. Is recommended.
[0224]
Although the high capillary suction foam may be in sheet form when combined with other absorbents such as osmotic absorbents (eg, hydrogel-forming absorbent polymers), in particularly preferred embodiments the polymer foam is It will be in particulate form and will be mixed with particles of the hydrogel-forming polymer to provide a mixture. That is, foams are initially prepared in sheet form, but these sheets can be processed to provide foam particles, which are then combined with a hydrogelled polymer. As discussed above, the foams useful herein and the processes for their preparation are described in US Pat. No. 5,387,207, TADesMarais entitled “HIGH SUCTION POLYMERIC FOAM MATERIALS”. Co-pending US patent application filed March 3, 1998 (P & G case) and TADesMarais et al. Entitled “Absorptive Materials for Dispersing Aqueous Liquids (ABSORBENT MATERIALS FOR DISTRIBUTING AQUEOUS LIQUIDS)” Is described in greater detail in co-pending US Patent Application No. (P & G case) filed March 1998. Foam particles are first formed into a sheet-like foam according to the teachings of these references, and then mechanically processed into the foam to provide particles of the desired dimensions (eg, pulverization, cutting, chopping). Others). Alternatively, the foam particles can be obtained, for example, from US Pat. No. 5,653,922 issued to Li et al. On August 5, 1997 and the disclosure of each of which is incorporated herein by reference. Can be prepared directly from the emulsion in the form of polymer microbeads as described in US Pat. Specific examples in the preparation of polymer foam / hydrogel-forming polymer blends are discussed in more detail below.
[0225]
Applicants have further discovered that the high surface area foam can optionally comprise a liquid so that the transfer of urine to other absorbents or osmotic absorbents of the storage absorbent member can be increased. The prewetting liquid partially fills the polymer foam and further increases the foam uptake rate without wishing to be tied to a particular theory. Ideally, polymer foams with pre-wetting liquids prevent microbial growth and prevent loss of volatile water, and are storage stable with sufficiently low water activity to prevent migration from foam over time. There must be. Water can be used as a prewetting liquid to provide absorption performance, but alone cannot meet other requirements.
[0226]
<Hydrogel-forming absorbent polymer>
The storage absorbent member of the present invention more preferably comprises at least one hydrogel-forming absorbent polymer (also referred to as a hydrogel-forming polymer). Hydrogel-forming polymers useful in the present invention include various water-insoluble but water-wettable polymers that can absorb large amounts of liquid. Such hydrogel-forming polymers are well known in the art, and any of these materials are useful in the high capillary suction absorbent member of the present invention.
[0227]
Hydrogel-forming absorbent polymer materials are also commonly referred to as “hydrocolloid” or “superabsorbent” materials such as polysaccharides such as carboxymethyl starch, carboxymethyl cellulose, and hydroxypropyl cellulose; polyvinyl alcohol and polyvinyl Nonionic types such as ethers; polyvinyl vinylidene, polyvinyl morpholinion, and cationic types such as N, N-dimethylaminoethyl or N, N-diethylaminopropyl acrylates and methacrylates and their respective fourths Grade salts can be included. Typically, hydrogel-forming absorbent polymers useful in the present invention have a plurality of anionic functional groups such as sulfonic acids, and more typically carboxy groups. Examples of polymers suitable for use herein include those prepared from polymerizable unsaturated acid-containing monomers. Accordingly, such monomers contain olefinically unsaturated acids and anhydrides containing at least one carbon-carbon olefinic double bond. More particularly, these monomers can be selected from olefinically unsaturated carboxylic acids and anhydrides, olefinically unsaturated sulfonic acids, and mixtures thereof. As noted above, the nature of the hydrogel-forming absorbent polymer is not critical to the members of the present invention. Nevertheless, the selection of the optimal polymer material may enhance the performance characteristics of the members of the present invention. The following describes the preferred properties of the absorbent polymer useful herein. These properties should not be construed as limiting; rather, they simply represent the progress that has occurred in absorbent polymer technology over the last few years.
[0228]
When preparing hydrogel-forming absorbent polymers here, some non-acidic monomers can also be included, usually in negligible amounts. Such non-acidic monomers include, for example, water-soluble or water-dispersible esters of acid-containing monomers and monomers that do not contain any carboxylic or sulfonic acid groups. Thus, any non-acidic monomer can contain monomers containing the following types of functional groups: carboxylic or sulfonate esters, hydroxyl groups, amide groups, amino groups, nitrile groups, quaternary ammonium Bases, aryl groups (eg, phenyl groups such as those derived from styrene monomers). These non-acidic monomers are well known materials, for example, US Pat. No. 4,076,663 (Masuda et al.) Issued February 28, 1978, both incorporated herein by reference, and 1977. U.S. Pat. No. 4,062,817 (Westerman) issued Dec. 13, 2003, is described in greater detail.
[0229]
Olefinically unsaturated carboxylic acids and carboxylic anhydride monomers include acrylic acid itself, methacrylic acid, ethacrylic acid, α-chloroacrylic acid, a-cyanoacrylic acid, β-methylacrylic acid (crotonic acid), α- Phenylacrylic acid, β-acryloxypropionic acid, sorbic acid, α-chlorosorbic acid, angelic acid, cinnamic acid, p-chlorocinnamic acid, β-sterylacrylic acid, itaconic acid, citroconic acid, mesaconic acid, glutaconic acid , Acrylic acid typified by aconitic acid, maleic acid, fumaric acid, tricarboxyethylene and maleic anhydride.
[0230]
Olefin unsaturated sulfonic acid monomers include aliphatic or aromatic vinyl sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, vinyl toluene sulfonic acid and styrene sulfonic acid; sulfoethyl acrylate, sulfoethyl methacrylate, sulfopropyl Acrylic and methacrylic sulfonic acids such as acrylate, sulfopropyl methacrylate, 2-hydroxy-3-methacryloxypropyl sulfonic acid and 2-acrylamido-2-methylpropane sulfonic acid are included.
[0231]
Preferred hydrogel-forming absorbent polymers for use in the present invention contain carboxy groups. These polymers include hydrolyzed starch-acrylonitrile graft copolymers, partially neutralized hydrolyzed starch-acrylonitrile graft copolymers, starch-acrylic acid graft copolymers, partially neutralized. Starch-acrylic acid graft copolymers, saponified vinyl acetate-acrylic ester copolymers, hydrolyzed acrylonitrile or acrylamide copolymers, slightly network cross-linked polymers of any of the above copolymers , Partially neutralized polyacrylic acid, and slightly neutralized polyacrylic acid slightly reticulated cross-linked polymers. These polymers can be used either alone or in the form of a mixture of two or more different polymers. Examples of these polymeric materials are US Pat. No. 3,661,875, US Pat. No. 4,076,663, US Pat. No. 4,093,776, US Pat. No. 4,666,983, and US Pat. This is disclosed in Japanese Patent No. 4,734,478.
[0232]
The most preferred polymeric materials for use in making the hydrogel-forming absorbent polymers are slightly reticulated crosslinked polymers of partially neutralized polyacrylic acid and their starch derivatives. Most preferably, the hydrogel-forming absorbent polymers are from about 50 to about 95%, preferably about 75% neutralized slightly network cross-linked polyacrylic acid (ie poly (sodium acrylate / acrylic acid)). ). The network crosslinks render the polymer substantially insoluble in water and further determine, in part, the absorption capacity and extractable polymer content characteristics of the hydrogel-forming absorbent polymer. Processes for network cross-linking these polymers and typical network cross-linking agents are described in greater detail in US Pat. No. 4,076,663.
[0233]
The hydrogel-forming absorbent polymer is preferably of one type (ie, homogeneous), but mixtures of polymers can also be used in the present invention. For example, in the present invention, mixtures of starch-acrylic acid graft copolymers and partially neutralized polyacrylic acid slightly reticulated crosslinked polymers can be used.
[0234]
The hydrogel forming polymer component may also be in the form of a mixed bed ion exchange composition comprising a cation exchange hydrogel forming absorbent polymer and an anion exchange hydrogel forming absorbent polymer. Such mixed bed ion exchange compositions are described, for example, in U.S. Patent Application No. (P & G Inc. 6975- “Under pressure of mounting” filed Jan. 7, 1998 by Hird et al., The disclosure of each of which is incorporated herein by reference. Absorbing polymer composition with high adsorption capacity (ABSORBENT POLYMER COMPOSITIONS HAVING HIGH SORPTION CAPACITIES UNDER AN APPLIED PRESSURE); and US patent application filed January 7, 1998 by Ashraf et al. (P & G case) 6976— “Absorptive Polymer Compositions with HIGH SORPTION CAPACITY AND HIGH FLUID PERMEABILITY UNDER AN APPLIED PRESSURE” with high adsorption capacity and high liquid permeability under loading pressure; and 1998 by Ashraf et al. US patent application filed Jan. 7 (P & G Case 6977- “High adsorption capacity and pressure under mounting pressure” And absorptive polymer composition with improved integrity in the swollen state (ABSORBENT POLYMER COMPOSITIONS WITH HIGH SORPTION CAPACITY UNDER AN APPLIED PRESSURE AND IMPROVED INTEGRITY IN THE SWOLLEN STATE).
[0235]
Hydrogel-forming absorbent polymers useful in the present invention can have a wide variety of sizes, shapes and / or forms. These polymers may be in the form of particles that do not have a large ratio of maximum dimension to minimum dimension (eg, granules, powders, particle intermolecular aggregates, particle intermolecular aggregates, etc.), and Fibers, sheets, films, foams, flakes and other shapes may be used. Hydrogel-forming absorbent polymers can also comprise a mixture with low levels of one or more additives such as, for example, powdered silica, surfactants, glues, binders, and the like. The components in this mixture may be physically and / or chemically bonded in such a way that the hydrogel-forming polymer component and the non-hydrogel-forming polymer additive are not easily physically separable.
[0236]
Hydrogel-forming absorbent polymers may be essentially non-porous (ie, not internally porous), or may be substantially internally porous.
[0237]
For particles as described above, particle size is defined as the dimension measured by sieve size analysis. Thus, for example, particles retained on a US standard test sieve with an opening of 710 microns (e.g., US Continuous Replacement Screen Symbol No. 25) are considered to have a size greater than 710 microns; Particles that pass through a sieve with an opening but on a sieve with an opening of 500 microns (eg, US Continuous Replacement Sieve Symbol No. 35) have a particle size between 500 and 710 μm. It is believed that; and particles that pass through a sieve with an opening of 500 microns are considered to have a size of less than 500 μm. The mass median particle size of a given sample of hydrogel-forming absorbent polymer particles is defined as the particle size that divides the sample in half on a mass basis; that is, half of the sample by weight has a particle size that is smaller than the mass median size. And the other half of the sample will have a particle size greater than the mass median size. When the 50% mass value does not correspond to the size of a US standard test sieve opening, typically the standard particle size plot method (where a constant sieve size opening is used to determine the mass median particle size). The cumulative weight percent of the particle sample that is retained or passed through the aperture is plotted on the paper against the size of the sieve aperture). These methods for measuring the size of hydrogel-forming absorbent polymer particles are described in US Pat. No. 5,061,259 (Goldman et al.) Issued Oct. 29, 1991, which is incorporated herein by reference. It is described in detail.
[0238]
For hydrogel-forming absorbent polymer particles useful in the present invention, the particles will generally have a size in the range of about 1 to about 2,000 μm, more preferably about 20 to about 1,000 μm. The mass median particle size will generally be from about 20 to about 1,500 μm, more preferably from about 50 μm to about 1,000 μm, even more preferably from about 100 μm to about 800 μm.
[0239]
If a significantly higher concentration of hydrogel-forming absorbent polymer is utilized in the absorbent member of the present invention (eg, 40%, 60% or more by weight), additional properties of the absorbent polymer are important May be. In such embodiments, the materials are disclosed in US Pat. No. 5,562,646 issued to Goldman et al. On Oct. 8, 1996, Goldman on Feb. 4, 1997, the disclosures of each of which are incorporated herein by reference. May have one or more of the characteristics described by U.S. Pat. No. 5,599,335.
[0240]
The base hydrogel-forming absorbent polymer can be formed by any conventional method. A typical and preferred process for producing these polymers is described in US Reissue Patent No. 32,649 (Brandt et al.), Issued April 19, 1988, which is hereby incorporated by reference in its entirety. U.S. Pat. No. 4,666,983 (Tsubakimoto et al.) Issued May 19, 1987, and U.S. Pat. No. 4,625,001 (Tsubakimoto et al.) Issued Nov. 25, 1986. ing.
[0241]
A preferred method for forming the base hydrogel-forming absorbent polymer is a method comprising an aqueous solution or other solution polymerization method. As described in US Reissue Pat. No. 32,649 referenced above, the aqueous solution polymerization process involves the use of an aqueous reaction mixture to carry out the polymerization. The aqueous reaction mixture is then subjected to polymerization conditions sufficient to produce a slightly network cross-linked polymer that is substantially insoluble in water in the mixture. The formed polymer mass is then micronized or chopped to form individual particles.
[0242]
More particularly, an aqueous polymerization process for producing a hydrogel-forming absorbent polymer comprises the preparation of an aqueous reaction mixture for performing the polymerization therein. One element of such a reaction mixture is an acidic group-containing monomer that will form the “backbone” of the hydrogel-forming absorbent polymer produced. The reaction mixture will generally comprise about 100 parts by weight of monomer. Another component of the aqueous reaction mixture comprises a network crosslinker. Network crosslinkers useful in forming hydrogel-forming absorbent polymers according to the present invention are the above-referenced US Reissue Patents 32,649, 4,666,983 and 4 , 625,001. The network crosslinker will generally be present in the aqueous reaction mixture in an amount of from about 0.001 mole percent to about 5 mole percent based on the total moles of monomer present in the aqueous mixture (to 100 parts by weight of monomer). Based on about 0.01 to about 20 parts by weight). Optional components of the aqueous reaction mixture include, for example, sodium, potassium and ammonium persulfates, caprylyl peroxide, benzoyl peroxide, hydrogen peroxide, cumene hydroperoxides, tertiary butyl diperphthalate, tertiary butyl perbenzoate, A free radical initiator comprising a peroxygen compound such as sodium peracetate, sodium percarbonate and others is provided. Other optional components of the aqueous reaction mixture include various non-acidic comonomers, including esters of essential unsaturated acidic functional group-containing monomers or other comonomers that do not contain any other carboxylic or sulfonic acid functional groups. It has.
[0243]
The aqueous reaction mixture undergoes polymerization conditions that are substantially insoluble in water but sufficient to produce a slightly reticulated crosslinked polymer in a water-swellable hydrogel-forming absorbent. Polymerization conditions are also discussed in more detail in the above three patents. Such polymerization conditions generally include the step of heating to a polymerization temperature of about 0 ° C. to about 100 ° C., more preferably about 5 ° C. to about 40 ° C. (thermal activation process). The polymerization conditions under which the aqueous reaction mixture is maintained can further include, for example, subjecting the reaction mixture or portions thereof to any conventional polymerization activation stimulus. X-ray, electron beam, ultraviolet light, or electromagnetic wave irradiation is a conventional alternative polymerization method.
[0244]
The acidic functional groups of the hydrogel-forming absorbent polymer formed in the aqueous reaction mixture are more preferably neutralized. Neutralization results in at least 25 mole percent, and more preferably at least about 50 mole percent of all monomers utilized to form a polymer that is acidic group-containing monomers that are neutralized with salt-forming cations. It can be performed in any conventional manner. Such salt forming cations include, for example, alkali metals, ammonium, substituted ammonium and amines as discussed in detail in US Reissue Pat. No. 32,649 referenced above.
[0245]
Preferably, a particular version of the hydrogel-forming absorbent polymer is produced using an aqueous solution polymerization process, but may also be polymerized using a multi-layer polymerization process such as, for example, an inverse emulsion polymerization process or an inverse suspension polymerization process. It is also possible to execute the process. In inverse emulsion polymerization or inverse suspension polymerization, an aqueous reaction mixture as described above is suspended in the form of small droplets in a substrate of an inert organic solvent that is immiscible with water, such as cyclohexane. Be made. The resulting hydrogel-forming absorbent polymer particles are generally spherical in shape. The reverse suspension polymerization method is described in U.S. Pat. No. 4,340,706 (Obayashi et al.) Issued July 20, 1982, March 19, 1985, all of which are incorporated herein by reference. U.S. Pat. No. 4,506,052 (Flesher et al.) Issued and U.S. Pat. No. 4,735,987 (Morita et al.) Issued Apr. 5, 1988 are described in great detail.
[0246]
The surface cross-linking of the initially formed polymers is a reasonably high porous hydrogel layer (“PHL”), performance under pressure (“PUP”) capacity and salt content that may be beneficial in the context of the present invention. A preferred process for obtaining hydrogel-forming absorbent polymers having flow conductivity (“SFC”) values. General methods suitable for carrying out surface cross-linking of hydrogel-forming absorbent polymers according to the present invention are described in U.S. Pat. No. 5,917,1985, which is hereby incorporated by reference in its entirety. No. 4,541,871 (Obayashi); PCT application WO 92/16565 (Stanley) published Oct. 1, 1992; PCT application No. WO 90/08789 (Tai) published Aug. 9, 1990 PCT application WO 93/05080 (Stanley) published March 18, 1993; US Pat. No. 4,824,901 (Alexander) issued April 25, 1989; January 1989 U.S. Pat. No. 4,789,861 (Johnson) issued on 17th; U.S. Pat. No. 4,587,308 (Makita) issued on 6 May 1986; U.S. Pat. No. 4,734,478 issued to Tsubakimoto; U.S. Pat. No. 5,164,459 issued to November 17, 1992 (Kimura et al.); Published on August 29, 1991 Published German Patent Application No. 4,020,780 (Dahmen); and published European Patent Application No. 509,708 (Gartner) published Oct. 21, 1992. See also US Pat. No. 5,562,646 issued on Oct. 8, 1996 (Goldmann et al.) And US Pat. No. 5,599,335 issued on Feb. 4, 1997 (Goldmann et al.). thing.
[0247]
Hydrogel-forming absorbent polymer particles prepared according to the present invention are typically substantially dry. The term “substantially dry” here means that the particles have a liquid content of less than about 50%, preferably less than about 20%, more preferably less than about 10% by weight of the particles, typically water or other It means having a solution content. Generally, the liquid content of the hydrogel-forming absorbent polymer particles is in the range of about 0.01% to about 5% by weight of the particles. Individual particles can be dried by any conventional method, such as by heating. Alternatively, if the particles are formed using an aqueous reaction mixture, water can be removed from the reaction mixture by azeotropic distillation. The polymer-containing aqueous reaction mixture can also be treated with a dehydrating solvent such as methanol. Combinations of these drying methods can also be used. The dehydrated mass of polymer can then be chopped or micronized to form substantially dry particles of the hydrogel-forming absorbent polymer.
[0248]
<Combination of high capillary suction materials>
While the materials described above can meet the requirements on their own (eg, pure hydrogel forming material, or pure foam material), preferred members for use as storage absorbent members comprise more than one material.
[0249]
The primary function of such a fluid storage member is to absorb bodily fluids drained directly or from other absorbent members (eg, fluid collection / distribution members) and then subject to the pressure normally encountered as a result of wearer movement. Even if it is to retain such fluid.
[0250]
Thus, a high capillary suction absorbent member can be made by a combination of a hydrogel forming material and a high surface area material.
[0251]
The amount of hydrogel-forming absorbent polymer included in the absorbent member can vary significantly. Furthermore, the concentration of hydrogel can also vary through certain members. In other words, one member can have regions of relatively high and relatively low hydrogel concentrations.
[0252]
When measuring the concentration of the hydrogel-forming absorbent polymer in a region of the absorbent member, any other component (eg, fiber, polymer foam, etc.) present in the region containing the hydrogel-forming polymer and hydrogelling polymer The weight percent of hydrogel-forming polymer compared to the bond weight of is used. With this in mind, the concentration of the hydrogel-forming absorbent polymer in a region of the absorbent member of the present invention is at least about 50%, at least about 60%, at least about 70%, based on the total weight of the absorbent member, Or at least about 80%.
[0253]
Despite the fact that the area of the absorbent member can have a fairly high concentration of hydrogel-forming absorbent polymer, if the high surface area material is fibrous, the absorbency in certain absorbent members The total polymer concentration (ie, the total weight of the hydrogel-forming absorbent polymer divided by the total weight of the absorbent member multiplied by 100%) is up to about 75% by weight, preferably up to about 70% by weight, and more Preferably it will be up to about 65% by weight. Thereafter, using these high surface area fiber-containing members, the concentration of the hydrogel-forming absorbent polymer is about 10 to about 75% by weight, more typically about 15 to about 70% by weight, and even more typically. It will be about 20 to about 65% by weight.
[0254]
In embodiments where the high surface area material is a polymer foam, the absorbent member is preferably at least about 1% by weight (on an aggregate basis), more preferably at least about 10% by weight, more preferably at least about 15 by weight. %, Even more preferably at least about 20% polymer foam by weight. Typically, such storage absorbent members are about 1 to about 98% by weight, more typically about 10 to 90% by weight, even more typically about 15 to about 85% by weight, even more More typically, it will comprise from about 20 to about 80% polymer foam material by weight. As noted above, these weight percent ranges are based on the aggregate weight of each material in the absorbent member; it is recognized that the area of the absorbent member may contain more and less material. ing.
[0255]
Of course, the relative levels of the absorbent polymer and the high surface area material are, for example, the absorption capacity of the hydrogel-forming absorbent polymer, the high specific surface area of the material used, the nature of the high surface area material (eg, sheet or particulate foam, particle size ) Directed by others. In this regard, a high level of hydrogel-forming absorbent polymer provides an absorbent member for producing a thin absorbent body to achieve the required level of capillary suction described above, but to provide such suction capacity. There must be sufficient high surface area material. Thus, high levels of hydrogel-forming polymer can be used when fairly high capillary suction foams are used. Conversely, if fairly low capillary suction fibers are used, a somewhat lower level of hydrogel-forming polymer will be used. (Of course, if both high surface area fibers and polymer foam are used, the total high surface area material level may also vary depending on the relative concentration of each of these materials.) Constant absorption It is the difference in capillary adsorption capacity between the polymer foam and the high surface area fibers that accounts for the different ranges of hydrogel-forming polymers used in the adhesive member.
[0256]
As another example of a material that provides blend integrity in an absorbent member comprising a mixture of hydrogel-forming polymer and high surface area fibers and / or particulate polymer foam, the member can comprise a thermoplastic material. Upon melting, at least a portion of this thermoplastic material moves to the intersection of each component component, typically due to interparticle or interfiber capillary gradients. These intersections become binding sites for the thermoplastic material. When cooled, the thermoplastic material at these intersections cures to form a binding site that holds the substrate of the material together.
[0257]
Any thermoplastic material useful herein may be in any of a variety of forms including particles, fibers, or a combination of particles and fibers. Thermoplastic fibers are a particularly preferred form because of their ability to form numerous binding sites. Suitable thermoplastic materials can be made from any thermoplastic polymer that can be melted at temperatures that will not extensively damage the material comprising the absorbent member. Preferably, the melting point of the thermoplastic material will be less than about 190 ° C, and preferably between about 75 ° C and about 175 ° C. In any event, the melting point of the thermoplastic material must not be lower than the temperature at which the thermally bonded absorbent structure will be stored when used in an absorbent body. The melting point of the thermoplastic material is typically about 50 ° C. or higher.
[0258]
Thermoplastic materials, and in particular thermoplastic fibers, are, for example, polyolefins such as polyethylene (eg PULPEX® and polypropylene), polyesters, copolyesters, polyvinyl acetate, ethyl ethyl acetate, polyvinyl chloride, polyvinyl chloride. Made from various thermoplastic polymers including vinylidene, polyacrylics, polyamides, copolyamides, polystyrenes, polyurethanes and any of the above copolymers such as vinyl chloride / vinyl acetate etc. One preferred thermoplastic binder fiber is as an approximately 20% mixture with 80% cellulosic fibers sold under the trademark KITTYHAWK® (from Weyerhaeuser CO.). PLEFAFIL® polyethylene available also Depending on the characteristics desired for the resulting thermally bonded absorbent member, suitable thermoplastic materials may be polyolefins such as polyethylene or polypropylene, poly Includes hydrophobic fibers made hydrophilic such as surfactant-treated or silica-treated thermoplastic fibers derived from acrylics, polyamides, polystyrenes, polyurethanes, etc. The surface of the hydrophobic thermoplastic fibers is, for example, fibers Nonionic or anionic by spraying the surfactant on the surface, dipping the fibers in the surfactant, or including the surfactant as part of the dissolved polymer when making the thermoplastic fiber It can be rendered hydrophilic by treatment with a surfactant such as a surfactant, which melts and resolidifies. , Surfactants will tend to remain on the surface of thermoplastic fibers, suitable surfactants include Brij (registered) manufactured by ICI Americas, Inc. of Wilmington, Delaware. Non-ionic surfactants such as 76 and various surfactants sold by Glyco Chemical, Inc. of Greenwich, Conn. Under the trademark Pegosperse® In addition to nonionic surfactants, anionic surfactants may also be used, such as thermoplastic fibers at a level of about 0.2 to about 1 g per square centimeter of thermoplastic fiber. Can be applied to.
[0259]
Suitable thermoplastic fibers can be made from a single polymer (monocomponent fibers) or can be made from a polymer greater than one (eg, bicomponent fibers). As used herein, “bicomponent fiber” means a thermoplastic fiber comprising a core fiber made from one polymer that is enclosed in a thermoplastic sheath made from a different polymer. Polymers with a sheath often melt at a lower temperature, which is different from polymers that can have a core. As a result, these bicomponent fibers provide thermal bonding due to the melting of the sheath polymer, while retaining the desirable strength characteristics of the core polymer.
[0260]
Bicomponent fibers suitable for use in the present invention can include sheath / core fibers having the following polymer combinations: polyethylene / polypropylene, polyethyl vinyl acetate / polypropylene, polyethylene / polyester, polypropylene / polyester, co-polymer. Polyester / polyester and others. Particularly suitable bicomponent thermoplastic fibers for use herein are those having a polypropylene or polyester core and a lower melting point copolyester, polyethyl vinyl acetate or polyethylene sheath (eg, DANAKLON®, CELBOND ( Registered trademark) or CHISSO (registered trademark) bicomponent fiber). These bicomponent fibers may be concentric or eccentric. As used herein, the terms “concentric” and “eccentric” relate to whether the sheath has a uniform or non-uniform thickness through the cross-section of the bicomponent fiber. Eccentric bicomponent fibers may be desirable when providing higher compressive strength when the fiber thickness is smaller. Bicomponent fibers suitable for use herein can be either not crimped (ie, straightened) or crimped (ie, bent). Bicomponent fibers can typically be crimped by typical textile means such as stuffer box methods or gear crimp methods to achieve primarily two-dimensional or "flat" crimps, for example. .
[0261]
In the case of thermoplastic fibers, their length may vary depending on the specific melting point and other properties desired for these fibers. Typically, these thermoplastic fibers have a length of about 0.3 to about 7.5 cm, preferably about 0.4 to about 3.0 cm, and most preferably about 0.6 to about 1.2 cm. Have Moreover, the characteristics including the melting point of these thermoplastic fibers can be adjusted by changing the fiber diameter (caliper). The diameter of these thermoplastic fibers is typically defined by either denier (grams per 9,000 meters) or decitex (grams per 10,000 meters). Suitable bicomponent thermoplastic fibers may have a dtex in the range of, for example, about 1.0 to about 20, preferably about 1.4 to about 10, and most preferably about 1.7 to about 3.3. it can.
[0262]
These thermoplastic materials, and particularly compression modules of thermoplastic fibers, may also be important. Thermoplastic fiber compression modules are not only their length and diameter, but also the composition and properties of the polymers or polymers from which they are made, the shape and structure of the fibers (eg, concentric or eccentric, crimped) Or uncrimped) and other factors. The differences in these thermoplastic fiber compression modules can be used to change the properties of each absorbent member and in particular the density properties during the preparation of the absorbent core.
[0263]
<Components and materials of other fluid processing members>
The storage absorbent member according to the present invention may include any other component that may be present in the absorbent web. For example, the reinforcing scrim can be placed in the storage absorbent member or between each absorbent member of the absorbent core. Such reinforcing scrims must be structured so as not to form an interfacial barrier against liquid movement, especially when placed between the absorbent members of the absorbent core. In addition, several binders can be used to provide dry and wet integrity to the absorbent core and / or the absorbent storage member itself. In particular, hydrophilic glue fibers may be used to provide a bond between high surface area materials and other absorbents such as osmotic absorbent materials. This is particularly important for certain high surface area materials. The amount of binder used is preferably as small as possible so as not to impair the capillary adsorption properties of the absorbent member. However, those skilled in the art will recognize that there are binders that may enhance the capillary adsorption properties of absorbent members such as fiberized hydrophilic glue with sufficiently high surface area. In this case, the high surface area hydrophilic glue may provide both liquid handling and integrity functions in one material. In addition, to prevent user concerns regarding loose particulate absorbent polymers, each absorbent member, or the entire absorbent core, can be permeable to liquids such as tissue paper sheets, unless capillary continuity is interrupted. It can also be wrapped in a sex sheet.
[0264]
Other optional components that can be included are materials for controlling odor, containing stool, and the like. To prevent further user concerns regarding loose particulate absorbent polymers, any absorbent member comprising a particulate osmotic absorbent or high surface area material, or the entire absorbent core, eg tissue paper It can also be encased in a liquid permeable sheet such as a sheet.
[0265]
When integrity is introduced by the binder material, suitable binders are described in US Pat. No. 5,560,878 issued Oct. 1, 1996 to Dragoo et al., Whose disclosure is incorporated herein by reference. Melt blow adhesive as described. The process for bonding the meltblown adhesive with the required hydrogel-forming polymer and high surface area material is also described in detail in the '878 patent.
[0266]
【Example】
<Sample 1,2,3-HIPE as distribution material>
Sample A below. 5-A. 7 is of the polymer foam type and is generally prepared as described in the experimental section of US Pat. No. 5,563,179 above. In general, the process comprises appropriate mixing of an aqueous phase containing selected salts with an oil phase containing selected monomers and emulsifiers. The aqueous phase typically contains an initiator such as potassium persulfate and an inorganic salt such as calcium chloride. The oil phase typically contains a mixture of monomers such as 2-ethylhexyl acrylate and cross-linking monomers such as divinylbenzene (containing ethyl styrene as an impurity) and 1,6-hexanediol diacrylate. . Adjuvants such as antioxidants, opacifiers, pigments, dyes, fillers and other generally inert chemicals can also be added to either phase.
[0267]
Separate streams of oil and water phases (typically heated between about 30 ° C. and about 90 ° C.) are sent to a dynamic mixing device. Complete mixing of the combined flow in the dynamic mixing device is achieved by a pin impeller. In order to control the density of the final foam produced, a ratio of water to oil phase called “water to oil ratio” or W: O is used. A detailed description of the apparatus and method for establishing the initial HIPE formation is described in more detail in the Examples section of US Pat. No. 5,563,179 mentioned above.
[0268]
Once the device mechanism is filled, agitation is started in the dynamic mixer using an impeller rotating at a specified RPM. The flow rate of the water phase is then 44.1 cm over a period of about 30 seconds.^ThreeThe oil phase flow rate is steadily increased to 1.25 g / sec over a period of about 1 minute. The back pressure created by the dynamic and static mixers at this point is typically about 3 to about 8 PSI (about 21 to about 55 kPa). The impeller speed is then adjusted to the desired RPM over 120 seconds. The back pressure of the system responds to this adjustment and remains constant thereafter.
[0269]
The HIPE from the static mixer is collected in 17 inch (43 cm) diameter and 7.5 inch (10 cm) circular polypropylene tabs with concentric inserts made of Celcon plastic. The insert has a bottom diameter of 5.0 inches (12.7 cm), a top diameter of 4.75 inches (12 cm), and a height of 6.75 inches (17.1 cm). The tab containing HIPE is held in a room maintained at 65 ° C. for 18 hours and cured to provide a HIPE polymer foam.
[0270]
The cured HIPE foam is removed from the tab. The foam at this point contains a residual aqueous phase (containing dissolved emulsifiers, electrolytes, initiator residue, and initiator). The foam is sliced into sheets of the desired thickness using a sharp reciprocating saw blade. These sheets are then subjected to compression between a series of two porous nip rolls with a vacuum that gradually reduces the residual aqueous phase content of the foam to about twice the weight of polymerized monomers (2 ×). At this point, the sheet is further 4% CaCl at 60 ° C.₂It is re-saturated with the solution and then squeezed with a series of three porous nip rolls equipped with a vacuum to about twice the aqueous phase content. Foam CaCl₂The content is between 2-10%.
[0271]
The HIPE foam is then air dried for about 16 hours or continuously heat dried. Such drying reduces the water content to about 4-20% by weight of the polymerized material.
[0272]
<Sample 1>:
Anhydrous calcium chloride (36.32 kg) and potassium persulfate (189 g) are dissolved in 378 liters of water. This provides an aqueous phase stream that is used in a continuous process to form a HIPE emulsion.
[0273]
Diglycerol monooleate emulsifier (480 g) in a monomer combination comprising distilled divinylbenzene (39% divinylbenzene and 61% ethylstyrene) (2640 g), 2-ethylhexyl acrylate (4720 g), and hexanediol diacrylate (640 g) , Ditallow dimethylammonium methylsulfate (80 g), and Tinuvin 765 (20 g) are added. Diglycerol monooleate emulsifier (Grindsted Products; Brabrand, Denmark) is about 81% diglycerol monooleate, 1% other diglycerol monoesters, 3% polyol And 15% other polyglycerol esters, giving a minimum oil / water interfacial tension value of about 2.7 dyne / cm and having an oil / water critical coagulation concentration of about 2.8% by weight . After mixing, the material combination is left to stabilize overnight. No visible residue is formed and the entire mixture is recovered and used as the oil phase in a continuous process to form a HIPE emulsion.
[0274]
Separate streams of oil phase (25 ° C.) and aqueous phase (53-55 ° C.) are fed to the dynamic mixing device. Complete mixing of the combined flows in the dynamic mixing device is achieved by a pin impeller. The pin impeller includes a cylindrical shaft having a length of about 36.5 cm and a diameter of about 2.9 cm. The shaft holds 6 rows of pins, 3 rows have 33 pins and 3 rows have 34 pins, and each of the three pins at each level is arranged at an angle of 120 ° to each other. , Each level having an adjacent level located 60 ° below the adjacent level separated by 0.03 mm and extending outwardly by a length of 2.3 cm from the central axis of the shaft The pin has a diameter of 0.5 cm. The pin impeller is attached to a cylindrical sleeve forming a dynamic mixing device, and the pin is further spaced 1.5 mm from the wall of the cylindrical sleeve.
[0275]
Dynamic mixing as shown in the figure in co-pending US patent application Ser. No. 08 / 716,510 (TADesMarais) filed Sep. 17, 1996 (incorporated herein by reference). A small portion of the effluent coming out of the device is collected and flows into the recirculation zone. A recirculation zone Waukesha pump returns this small portion to the entry point of the oil and water phase flow into the dynamic mixing zone.
[0276]
The spiral static mixer is mounted downstream from the dynamic mixing device to provide back pressure to the dynamic mixing device and to provide improved incorporation of components into the final formed HIPE. The static mixer (TAH Industries Model 100-812) has 12 elements with an outer diameter of 1 inch (2.5 cm). A hose is attached downstream of the static mixer to facilitate delivery of the emulsion to the equipment used for curing. Optionally, an additional static mixer is used to provide additional back pressure to maintain the filled hose. The optional static mixer may be a 1 inch (2.5 cm) pipe 12 element mixer (McMaster-Carr Model 3529K53).
[0277]
The combined mixing and recirculation mechanism is filled with oil and water phases at a ratio of 4 parts water to 1 part oil. The dynamic mixing device is evacuated so that air can escape while the device is completely filled. The flow rate during filling is 7.57 g / sec for the oil phase and 30.3 cm for the water phase.^Three/ Sec.
[0278]
Once the device mechanism is filled, rotate the impeller at 850 RPM to start stirring in the dynamic mixer, about 30 cm^ThreeStart recirculation at a rate of / sec. After that, the flow rate of the water phase is 151.3 cm over about 1 minute.^ThreeThe oil phase flow rate is reduced to 2.52 g / sec over about 3 minutes. The recirculation rate is 150 cm during the latter time^ThreeSteadily increase to / sec. The back pressure created by the dynamic zone and static mixer at this point is about 4.9 PSI (33.8 kPa), which represents the total pressure drop of the system. After that, the speed of the Waukesha pump is steadily reduced to about 75 cm.^ThreeA recirculation rate of / sec is produced.
[0279]
The flow of HIPE from the static mixer at this point was 40 inches (102 cm) in diameter and 12 inches in height with a removable side that was very similar to the mold that was used to open the bottom used in cake making. Collected in 5 inch (31.8 cm) round polyethylene tabs. A pipe-like polyethylene insert with a diameter of 12.5 inches (31.8 cm) at the bottom is firmly fixed in the center of the bottom surface and has a height of 12.5 inches (31.8 cm). The HIPE-containing tub is maintained for 18 hours in a room maintained at 65 ° C., causing polymerization to form a foam.
[0280]
The cured HIPE foam is removed from the curing tab. The foam at this point has a residual aqueous phase (including dissolved emulsifiers, electrolytes, initiator residues and initiator) of about 55 to 65 times the weight of polymerized monomer. The foam is sliced into 0.2 inch (5.1 mm) thick sheets using a sharp reciprocating saw blade. These sheets are then subjected to compression with a series of two porous nip rolls equipped with a vacuum that gradually reduces the residual aqueous phase content of the foam to about 3 times the weight of the polymerized material (3 ×). At this point, the sheet is further 4% CaCl at 60 ° C.₂The solution is re-saturated and squeezed with a series of three porous nip rolls equipped with vacuum to an aqueous phase content of about 1.5 to 2 times. Foam CaCl₂The content is 6-10%.
[0281]
The foam remains compressed to a thickness of about 0.027 inches (0.069 cm) after the final nip. The foam is then air dried for about 16 hours. Such drying reduces the water content to about 9-17% by weight of the polymerized material. At this point, the foam sheet can be extremely draped.
[0282]
<Sample 2>:
Anhydrous calcium chloride (36.32 kg) and potassium persulfate (189 g) are dissolved in 378 liters of water. This provides an aqueous phase stream that is used in a continuous process to form a HIPE emulsion.
[0283]
Diglycerol monooleate emulsifier in a monomer combination comprising distilled divinylbenzene (42.4% divinylbenzene and 57.6% ethylstyrene) (2640 g), 2-ethylhexyl acrylate (4400 g), and hexanediol diacrylate (960 g) (640 g), tallow dimethyl ammonium methyl sulfate (80 g), and Tinuvin 765 (20 g) are added. Diglycerol monooleate emulsifier (Grindsted Products; Brabrand, Denmark) is about 81% diglycerol monooleate, 1% other diglycerol monoesters, 3% polyol And 15% other polyglycerol esters, giving a minimum oil / water interfacial tension value of about 2.7 dyne / cm and having an oil / water critical coagulation concentration of about 2.8% by weight . After mixing, this combination of materials is left to stabilize overnight. No visible residue is formed and the entire mixture is recovered and used as the oil phase in a continuous process to form a HIPE emulsion.
[0284]
Separate streams of oil phase (25 ° C.) and aqueous phase (75-77 ° C.) are fed to the dynamic mixing device. Complete mixing of the combined flows in the dynamic mixing device is achieved by a pin impeller. The pin impeller includes a cylindrical shaft having a length of about 36.5 cm and a diameter of about 2.9 cm. The shaft holds 6 rows of pins, 3 rows have 33 pins and 3 rows have 34 pins, with each of the three pins at each level arranged at an angle of 120 ° to each other. , Each level having an adjacent level located 60 ° below the adjacent level separated by 0.03 mm and extending outwardly by a length of 2.3 cm from the central axis of the shaft The pin has a diameter of 0.5 cm. The pin impeller is attached to a cylindrical sleeve forming a dynamic mixing device, and the pin is further spaced 1.5 mm from the wall of the cylindrical sleeve.
[0285]
Dynamic mixing as shown in the figure in co-pending US patent application Ser. No. 08 / 716,510 (TADesMarais) filed Sep. 17, 1996 (incorporated herein by reference). A small portion of the effluent coming out of the device is collected and flows into the recirculation zone. A recirculation zone Waukesha pump returns this small portion to the entry point of the oil and water phase flow into the dynamic mixing zone.
[0286]
The spiral static mixer is mounted downstream from the dynamic mixing device to provide back pressure to the dynamic mixing device and to provide improved incorporation of components into the final formed HIPE. Static mixers (TAH Industries model 101-212) typically have 12 elements with an outer diameter of 1.5 inches (3.8 cm), but 7 inches (17 .8 cm) was removed. A hose is attached downstream of the static mixer to facilitate delivery of the emulsion to the equipment used for curing. Optionally, an additional static mixer is used to provide additional back pressure to maintain the filled hose. Any static mixer may be the same as the first without modification.
[0287]
The combined mixing and recirculation mechanism is filled with oil and water phases at a ratio of 4 parts water to 1 part oil. The dynamic mixing device is evacuated so that air can escape while the device is completely filled. The flow rate during filling is 7.57 g / sec for the oil phase and 30.3 cm for the water phase.^Three/ Sec.
[0288]
Once the device mechanism is filled, the impeller is rotated at 800 RPM to start stirring in the dynamic mixer, about 30 cm^ThreeStart recirculation at a rate of / sec. After that, the flow rate of the water phase is 151.3 cm over about 1 minute.^ThreeThe oil phase flow rate is reduced to 2.52 g / sec over about 3 minutes. During this latter period, the recirculation rate is about 150 cm.^ThreeSteadily increase to / sec. At this point, the back pressure created by the dynamic zone and the static mixer is about 4.2 PSI (29 kPa), which represents the total pressure drop of the system.
[0289]
The flow of HIPE from the static mixer at this point was 40 inches (102 cm) in diameter and 12 inches in height with a removable side that was very similar to the mold that was used to open the bottom used in cake making. Collected in 5 inch (31.8 cm) round polyethylene tabs. A pipe-like polyethylene insert with a diameter of 12.5 inches (31.8 cm) at the bottom is firmly fixed in the center of the bottom surface and has a height of 12.5 inches (31.8 cm). The HIPE-containing tub is maintained for 18 hours in a room maintained at 65 ° C., causing polymerization to form a foam.
[0290]
The cured HIPE foam is removed from the curing tab. The foam at this point has a residual aqueous phase (including dissolved emulsifiers, electrolytes, initiator residues and initiators) that is approximately 58-62 times (58-62 ×) the weight of polymerized monomer. The foam is sliced into 0.2 inch (5.1 mm) thick sheets using a sharp reciprocating saw blade. These sheets are then subjected to compression with a series of two porous nip rolls equipped with a vacuum that gradually reduces the residual aqueous phase content of the foam to about 6 times the weight of the polymerized material (6 ×). At this point, the sheet is further 1.5% CaCl at 60 ° C.₂The solution is re-saturated and squeezed with a series of three porous nip rolls equipped with a vacuum to an aqueous phase content of about twice. Foam CaCl₂The content is between 3-6%.
[0291]
The foam remains compressed to a thickness of about 0.047 inches (0.071 cm) after the final nip. The foam is then air dried for about 16 hours. Such drying reduces the water content to about 9-17% by weight of the polymerized material. At this point, the foam sheet can be extremely draped.
[0292]
<Sample 3>:
Anhydrous calcium chloride (36.32 kg) and potassium persulfate (189 g) are dissolved in 378 liters of water. This provides an aqueous phase stream that is used in a continuous process to form a HIPE emulsion.
[0293]
Diglycerol monooleate emulsifier in a monomer combination comprising distilled divinylbenzene (42.4% divinylbenzene and 57.6% ethylstyrene) (2640 g), 2-ethylhexyl acrylate (4400 g), and hexanediol diacrylate (960 g) (640 g), tallow dimethylammonium methyl sulfate (80 g), and Tinuvin 765 (40 g) are added. Diglycerol monooleate emulsifier (Grindsted Products; Brabrand, Denmark) is about 81% diglycerol monooleate, 1% other diglycerol monoesters, 3% polyol And 15% other polyglycerol esters, giving a minimum oil / water interfacial tension value of about 2.7 dyne / cm and having an oil / water critical coagulation concentration of about 2.8% by weight . After mixing, this combination of materials is left to stabilize overnight. No visible residue is formed and the entire mixture is recovered and used as the oil phase in a continuous process to form a HIPE emulsion.
[0294]
Separate streams of oil phase (25 ° C.) and aqueous phase (75-77 ° C.) are fed to the dynamic mixing device. Complete mixing of the combined flows in the dynamic mixing device is achieved by a pin impeller. The pin impeller includes a cylindrical shaft having a length of about 21.6 cm and a diameter of about 1.9 cm. The shaft holds 6 rows of pins, 3 rows have 21 pins and 3 rows have 21 pins, with each of the three pins at each level arranged at an angle of 120 ° to each other. Each level extending outwardly at a length of 1.4 cm from the central axis of the shaft, with adjacent levels located 60 ° below the adjacent levels separated by 0.03 mm The pin has a diameter of 0.5 cm. The pin impeller is attached to a cylindrical sleeve forming a dynamic mixing device, and the pin is further spaced 3 mm from the wall of the cylindrical sleeve.
[0295]
Shown in the figure in co-pending US patent application Ser. No. 08 / 716,510 (TADesMarais) filed Sep. 17, 1996, which is incorporated herein by reference. As shown, a small portion of the effluent coming out of the dynamic mixing device is collected and flows into the recirculation zone. A recirculation zone Waukesha pump returns this small portion to the entry point of the oil and water phase flow into the dynamic mixing zone.
[0296]
The spiral static mixer is mounted downstream from the dynamic mixing device to provide back pressure to the dynamic mixing device and to provide improved incorporation of components into the final formed HIPE. A static mixer (TAH Industries Model 070-821) modified by cutting 2.4 inches (6.1 cm) from the initial length has a length of 14 inches (35.6 cm) and an outer diameter of 0.1 mm. 5 inches (1.3 cm).
[0297]
The combined mixing and recirculation mechanism is filled with oil and water phases at a ratio of 4 parts water to 1 part oil. The dynamic mixing device is evacuated so that air can escape while the device is completely filled. The flow rate during filling is 1.89 g / sec for the oil phase and 7.56 cm for the water phase.^Three/ Sec.
[0298]
Once the device mechanism is filled, the impeller is rotated at 1,000 RPM to start stirring in the dynamic mixer, approximately 8 cm^ThreeStart recirculation at a rate of / sec. Thereafter, the flow rate of the water phase is steadily increased to 45.4 cm 3 / sec over about 1 minute, and the flow rate of the oil phase is further decreased to 0.6 g / sec over about 3 minutes. During this latter period, the recirculation rate is about 45 cm.^Three/ Sec is steadily increased. The back pressure created by the dynamic zone and static mixer at this point is about 2.9 PSI (20 kPa), which represents the total pressure drop of the system.
[0299]
The flow of HIPE from the static mixer at this point was a round polypropylene tab 17 inches (43 cm) in diameter and 7.5 inches (10 cm) in height with a concentric insert made from Celcon plastic. To be collected. An insert having a diameter of 5 inches (12.7 cm) at the bottom and a diameter of 4.75 inches (12 cm) at the top is 6.75 inches (17.1 cm) in height. The HIPE-containing tub is maintained for 18 hours in a room maintained at 65 ° C., causing polymerization to form a foam.
[0300]
The cured HIPE foam is removed from the curing tab. The foam at this point has a residual aqueous phase (including dissolved emulsifiers, electrolytes, initiator residues and initiator) that is approximately 70-80 times (70-80 ×) the weight of polymerized monomer. The foam is sliced into 0.185 inch (4.7 mm) thick sheets using a sharp reciprocating saw blade. These sheets are then subjected to compression with a series of two porous nip rolls equipped with a vacuum that gradually reduces the residual aqueous phase content of the foam to about 3 times the weight of the polymerized material (3 ×). At this point, the sheet is further 1.5% CaCl at 60 ° C.₂The solution is re-saturated and squeezed with a series of three porous nip rolls equipped with a vacuum to an aqueous phase content of about twice. Foam CaCl₂The content is 3-5%.
[0301]
The foam remains compressed to a thickness of about 0.031 inches (0.079 cm) after the final nip. The foam is then air dried for about 16 hours. Such drying reduces the water content to about 9-17% by weight of the polymerized material. At this point, the foam sheet can be extremely draped.
[0302]
<High Capillary Suction Storage Member (Sample S.)>
<Sample S. 1 Storage Absorbing Member Comprising Glass Superfine Fiber>
In this example, high capillary suction with high surface area glass ultrafine fibers formed using a hydrogel-forming absorbent polymer and a wet end molding process to increase density and structure over conventional air deposition processes. The absorbent member will be described. In order to construct such hydrogel-forming absorbent members that contain members addressed to the homogeneous distribution of the absorbent polymer in a glass microfiber substrate, the following method is followed.
[0303]
4.0 g of ASAP 2300 (available from Chemdal LTD, a subsidiary of American Colloid Co., Arlington Heights, Ill .; and The Procter & Gamble, Cincinnati, Ohio CO.) Papermaking technology division) and 4.0 g of glass microfiber (manufactured by Manville Sales Corp., Denver, Colorado, “Q-FIBERS, code 108, (Available as 110 Bulk)) about 500 ml of 3A alcohol (95% ethanol, 5% methanol), or similar liquids that will not reduce or absorb the structure or composition of isopropanol or related polymers 3 gallon commercial brand warner with explosion resistance (Warner) is combined in mixer. Stir the mixture at low speed for about 5 minutes. The mixture is equipped with an 80 mesh nylon molding wire (available from Appleton Manufacturing Division of Productive Solutions, Inc., Nina, Wyoming) at the bottom of the upper portion of the paper box. It is poured into a 6 inch × 6 inch “Paper Formation Box”. The liquid level is about 8 inches above the screen with the addition of 3A alcohol, or a suitable solution. Mix the solution thoroughly at the top of the paper box using a paddle before draining the liquid. The valve is opened below the forming wire to quickly drain the liquid and ensure uniform settling on the forming wire. The screen is removed from the “paper box” and pulled across a vacuum source to remove loosely held liquid and desiccant (eg, Sigma Chem, 63178 St. Louis, Missouri) to ensure uniform moisture content. Air dry overnight in a drier containing Sigme Chem. Co. DRIERITE. Once dried, the absorbent member is removed from the molding screen. In order to measure the capillarity absorption capacity, a 5.4 cm cylindrical structure is drilled from this member with an arch punch.
[0304]
<Sample S. 2 Preparation of high surface area foam from HIPE>
Anhydrous calcium chloride (36.32 kg) and potassium persulfate (189 g) are dissolved in 378 liters of water. This provides an aqueous phase stream that is used in a continuous process to form a HIPE emulsion.
[0305]
Diglycerol monooleate in a monomer combination comprising distilled divinylbenzene (42.4% divinylbenzene and 57.6% ethylstyrene) (2640 g), 2-ethylhexyl acrylate (4400 g), and hexanediol diacrylate (960 g) Add emulsifier (480 g), tallow dimethylammonium methylsulfate (80 g), and Tinuvin 765 (20 g). Diglycerol monooleate emulsifier (Grindsted Products; Brabrand, Denmark) is about 81% diglycerol monooleate, 1% other diglycerol monoesters, 3% polyol And 15% other polyglycerol esters, giving a minimum oil / water interfacial tension value of about 2.7 dyne / cm and having an oil / water critical coagulation concentration of about 2.8% by weight . After mixing, this combination of materials is left to stabilize overnight. No visible residue is formed and the entire mixture is recovered and used as the oil phase in a continuous process to form a HIPE emulsion.
[0306]
Separate streams of oil phase (25 ° C.) and aqueous phase (53-55 ° C.) are fed to the dynamic mixing device. Complete mixing of the combined flows in the dynamic mixing device is achieved by a pin impeller. The pin impeller includes a cylindrical shaft having a length of about 36.5 cm and a diameter of about 2.9 cm. The shaft holds 6 rows of pins, 3 rows have 33 pins and 3 rows have 34 pins, with each of the three pins at each level arranged at an angle of 120 ° to each other. , Each level having an adjacent level located 60 ° below the adjacent level separated by 0.03 mm and extending outwardly by a length of 2.3 cm from the central axis of the shaft The pin has a diameter of 0.5 cm. The pin impeller is attached to a cylindrical sleeve forming a dynamic mixing device, and the pin is further spaced 1.5 mm from the wall of the cylindrical sleeve.
[0307]
As shown in the figure in co-pending US patent application Ser. No. 08 / 716,510 filed by DesMarais on Sep. 17, 1996, the disclosure of which is incorporated by reference as part of this specification. At the same time, a small portion of the effluent exiting the dynamic mixing device is recovered and flows into the recirculation zone. A recirculation zone Waukesha pump returns this small portion to the entry point of the oil and water phase flow into the dynamic mixing zone.
[0308]
The static mixer (TAH Industries Model 100-812) has 12 elements with an outer diameter of 1 inch (2.5 cm). A hose is attached downstream of the static mixer to facilitate delivery of the emulsion to the equipment used for curing. Optionally, an additional static mixer is used to provide additional back pressure to maintain the filled hose. The optional static mixer may be a 1 inch (2.5 cm) pipe, 12 element mixer (McMaster-Carr, Aurora, Ohio, model 3529K53).
[0309]
The combined mixing and recirculation mechanism is filled with oil and water phases at a ratio of 4 parts water to 1 part oil. The dynamic mixing device is evacuated so that air can escape while the device is completely filled. The flow rate during filling is 7.57 g / sec for the oil phase and 30.3 cm for the water phase.^Three/ Sec.
[0310]
Once the device mechanism is filled, rotate the impeller at 1750 RPM to start stirring in the dynamic mixer, about 30 cm^ThreeStart recirculation at a rate of / sec. After that, the flow rate of the water phase is 151.3 cm over about 1 minute.^ThreeThe oil phase flow rate is reduced to 3.03 g / sec over about 3 minutes. The recirculation rate is about 150 cm during the latter time^ThreeSteadily increase to / sec. The back pressure created by the dynamic zone and static mixer at this point is about 19.9 PSI (137 kPa), which represents the total pressure drop of the system. The speed of the Waukesha pump (model 30) then decreases steadily to about 75 cm^ThreeA recirculation rate of / sec is produced.
[0311]
The flow of HIPE from the static mixer at this point was 40 inches (102 cm) in diameter and 12 inches in height with a removable side that was very similar to the mold that was used to open the bottom used in cake making. Collected in 5 inch (31.8 cm) round polyethylene tabs. A pipe-like polyethylene insert with a diameter of 12.5 inches (31.8 cm) at the bottom is firmly fixed in the center of the bottom surface and has a height of 12.5 inches (31.8 cm). The HIPE-containing tub is maintained in a room maintained at 65 ° C. for 18 hours to effect polymerization and form a foam.
[0312]
The cured HIPE foam is removed from the curing tab. The foam at this point has a residual aqueous phase (including dissolved emulsifiers, electrolytes, initiator residues and initiator) of about 48-52 times (48-52 ×) the weight of polymerized monomer. The foam is sliced into 0.185 inch (4.7 mm) thick sheets using a sharp reciprocating saw blade. These sheets are then subjected to compression with a series of two porous nip rolls equipped with a vacuum that gradually reduces the residual aqueous phase content of the foam to about 6 times the weight of the polymerized material (6 ×). At this point, the sheet is further 1.5% CaCl at 60 ° C.₂The solution is re-saturated and squeezed with a series of three porous nip rolls equipped with a vacuum to a water phase content of about 4 times. Foam CaCl₂The content is 8-10%.
[0313]
The foam remains compressed to a thickness of about 0.021 inches (0.053 cm) after the final nip. The foam is then air dried for about 16 hours. Such drying reduces the water content to about 9-17% by weight of the polymerized material. At this point, the foam sheet can be extremely draped and "thin-after-drying".
[0314]
<Sample S. 3 Preparation of high surface area foam from HIPE>
The aqueous and oil phase streams used in the continuous process to form the HIPE emulsion are described in Example S.1. Prepare according to 2. Separate streams of oil phase (25 ° C.) and aqueous phase (53-55 ° C.) were obtained from Example S.I. 2 to a dynamic mixing device.
[0315]
Once the device mechanism is filled, rotate the impeller at 1700 RPM to start stirring in the dynamic mixer, about 30 cm^ThreeStart recirculation at a rate of / sec. After that, the flow rate of the water phase is 151.3 cm over about 1 minute.^ThreeThe oil phase flow rate is reduced to 3.36 g / sec over about 3 minutes. The recirculation rate is about 150 cm during the latter time^ThreeSteadily increase to / sec. At this point, the back pressure created by the dynamic zone and static mixer is about 19.7 PSI (136 kPa), which represents the total pressure drop of the system. The speed of the Waukesha pump (model 30) then decreases steadily to about 75 cm^ThreeA recirculation rate of / sec is produced.
[0316]
The flow of HIPE from the static mixer at this point is the sample S.P. Collected as described in 2 and cured to polymer foam.
[0317]
The cured HIPE foam is removed from the curing tab. The foam at this point has a residual aqueous phase (including dissolved emulsifiers, electrolytes, initiator residues and initiator) that is approximately 43-47 times (43-47 ×) the weight of polymerized monomer. The foam is sliced into 0.185 inch (4.7 mm) thick sheets using a sharp reciprocating saw blade. These sheets are then subjected to compression with a series of two porous nip rolls equipped with a vacuum that gradually reduces the residual aqueous phase content of the foam to about 6 times the weight of the polymerized material (6 ×). At this point the sheet is further 1.5% CaCl at 60 ° C.₂The solution is re-saturated and squeezed with a series of three porous nip rolls equipped with vacuum to an aqueous phase content of about 4 times. Foam CaCl₂The content is 8-10%.
[0318]
The foam remains compressed to a thickness of about 0.028 inches (0.071 cm) after the final nip. The foam is then air dried for about 16 hours. Such drying reduces the water content to about 9-17% by weight of the polymerized material. At this point, the foam sheet can be extremely draped and "thin-after-drying".
[0319]
<Sample S. 4 Preparation of high surface area foam from HIPE>
The aqueous and oil phase streams used in the continuous process to form the HIPE emulsion are described in Example S.1. Prepare according to 2. Separate streams of oil phase (25 ° C.) and aqueous phase (53-55 ° C.) were obtained from Example S.I. 2 to a dynamic mixing device.
[0320]
Once the device mechanism is filled, rotate the impeller at 1750 RPM to start stirring in the dynamic mixer, about 30 cm^ThreeStart recirculation at a rate of / sec. After that, the flow rate of the water phase is 151.3 cm over about 1 minute.^ThreeThe oil phase flow rate is reduced to 3.78 g / sec over about 3 minutes. The recirculation rate is about 150 cm during the latter time^ThreeSteadily increase to / sec. At this point, the back pressure created by the dynamic zone and static mixer is about 18.7 PSI (129 kPa), which represents the total pressure drop of the system. The speed of the Waukesha pump (model 30) then decreases steadily to about 75 cm^ThreeA recirculation rate of / sec is produced.
[0321]
The flow of HIPE from the static mixer at this point is the sample S.P. 2 and collected into a polymer foam.
[0322]
The cured HIPE foam is removed from the curing tab. The foam at this point has a residual aqueous phase (including dissolved emulsifiers, electrolytes, initiator residues and initiator) of about 38-42 times (38-42 ×) the weight of polymerized monomer. The foam is sliced into 0.185 inch (4.7 mm) thick sheets using a sharp reciprocating saw blade. These sheets are then subjected to compression with a series of two porous nip rolls equipped with a vacuum that gradually reduces the residual aqueous phase content of the foam to about 6 times the weight of the polymerized material (6 ×). At this point, the sheet is further 1.5% CaCl at 60 ° C.₂The solution is re-saturated and squeezed with a series of three porous nip rolls equipped with a vacuum to a water phase content of about 4 times. Foam CaCl₂The content is 8-10%.
[0323]
The foam remains compressed to a thickness of about 0.028 inches (0.071 cm) after the final nip. The foam is then air dried for about 16 hours. Such drying reduces the water content to about 9-17% by weight of the polymerized material. At this point, the foam sheet can be extremely draped and "thin-after-drying".
[0324]
<Sample S. 5. Storage Absorbing Member Comprising High Surface Area Polymer Foam Material>
In this example, the hydrogel-forming absorbent polymer and sample S.I. A high capillary suction absorbent member comprising a high suction polymer foam prepared according to 3 is described. To construct a hydrogel-forming positive absorbent polymer containing members that approach the relatively homogeneous distribution of the absorbent polymer and polymer foam, the following method is followed:
A mixer (model Osterizer 848-36L) equipped with a 1.25 liter bottle already containing 1 liter of 2% calcium chloride solution in it, 10 g of air-dried polymer foam (sample above) S.3 prepared). After confirming that all foam material is submerged in the liquid, stir for 10 seconds at “Liquify” (high setting) and then for 5 seconds at “Grate” setting. The resulting slurry is then transferred to a Buchner funnel (Coors USA model 60283) lined with paper towels. Approximately 500 ml of liquid is drained freely from the sample. The sample is then coated with a rubber membrane and a vacuum (about 500 mm Hg or about 66 kPa) is applied to dehydrate the sample to a weight of 50-60 g.
[0325]
Return the sample to the dry mixer bottle and disperse with agitation set to “Liquify” while the bottle and mixer body are inverted several times or upright to disperse the sample into almost individual particles. Or return. The dispersed sample is then air dried under ambient conditions, after which the foam particles provide a storage absorbent member composed of a homogeneous mixture of 50% by weight hydrogel-forming polymer and 50% by weight high surface area polymer foam. For the hydrogel-forming absorbent polymer (ASAP 2300, available from Chemdal Corporation, Palantine, Ill .; and from the Paper Technology Division of The Procter & Gamble CO., Cincinnati, Ohio) Also available).
[0326]
<Sample S. 6 Storage Absorption Member Having High Surface Area Fibrette>
<Fibret>
This example describes a high capillary suction absorbent member comprising a hydrogel-forming absorbent polymer and a high surface area fibrette. To provide a storage and absorbent member composed of a homogenous mixture of 50% by weight hydrogel-forming polymer and 50% by weight fibrette, Hoechst (Hoechst) as cellulose acetate Fibrets®. High surface area fibrettes available from Celanese Cop .; Charlotte, North Carolina), available from Hydrogel-Forming Absorbent Polymer (ASAP 2300, Chemdal Corporation, Parantin, Ill .; and The Procter & Cincinnati, Ohio Combined with the paper technology division of The Procter & Gamble CO.
[0327]
<Structure>
As described in the general description section, it is assumed that these cores contain collection / distribution areas that are in liquid communication with the liquid storage areas and the materials used in these areas are Given that the requirements are met, the absorbent core can be configured with a wide range of possibilities. Accordingly, such a core can be constructed from each material in a layered arrangement with basis weight and size tailored to the intended use requirements as described above.
[0328]
A particular core structure useful for baby diapers of a size commonly referred to as MAXI has a rectangular shape with a length of about 450 mm and a width of about 100 mm. At this time, the collection / distribution region is composed of one layer of material having a similarly rectangular dimension covering the entire absorbent core. The liquid storage area may also be a rectangle that extends beyond the entire size of the absorbent core underneath the collection / distribution area as one layer. The thickness of the material may vary across the length and / or width of the absorbent core, but in a simple construction it is a uniform thickness throughout the absorbent core.
[0329]
Essential to the function is that the collection / distribution material and the storage material are selected according to their capillary suction characteristics as described above.
[0330]
With a specially selected sample as described above, every individual dispensing material sample can be combined with any of the respective storage materials and provide further adequate performance.
[0331]
<Test method>
Unless otherwise specified, tests are conducted under controlled experimental conditions at room temperature of about 23 +/− 2 ° C. and relative humidity of 50 +/− 10%. Specimens are stored under these conditions for at least 24 hours prior to testing.
[0332]
<Preparation of synthetic urine>
Unless otherwise specified, the special synthetic urine used in this test method is commonly known as Jayco SynUrine and is obtained from the Jayco Pharmaceuticals Company in Camp Hill, PA. Is possible. The formula for synthetic urine is as follows: 2.0 g / l KCl: 2.0 g / l Na₂SO_Four0.85 g / l (NH_Four) H₂PO_Four0.15 g / l (NH_Four) H₂PO_Four0.19 g / l CaCl₂And 0.23 g / l MgCl₂It is. All chemicals are special grade reagents. The pH of synthetic urine is in the range of 6.0 to 6.4.
[0333]
<Vertical wicking time and vertical wicking capacity>
Vertical wicking time was required for the colored test solution (eg, synthetic urine) in the reservoir to wick a 15 cm vertical distance through the test specimen of the specified size foam (capillary wicking like a wick) Measure by measuring time. The vertical wicking test method is described in detail in the Test Method section of US Pat. No. 5,387,207 (incorporated by reference) above, but here it is performed at 31 ° C. instead of 37 ° C. The vertical wicking capacity of the material for a given height is also the vertical wicking capacity described in the test method section of US Pat. No. 5,387,207, except that the test is performed at 31 ° C. instead of 37 ° C. Measure using test. Finally, the washing and re-drying steps described in the cited patent are not performed. The remarkable vertical wicking capacity value is the capacity achieved at a height of 15 cm in equilibrium. The result is the unit at a height of 15 cm (g / cm²/ Sec).
[0334]
<Simple liquid penetration test>
This simple permeability test provides a measure for the permeability for two special conditions: the permeability is for a wide range of porous materials that are 100% saturated (eg, nonwovens made from synthetic fibers, or cellulosic structures), or Measured for materials that reach different degrees of saturation with proportional changes in calipers without filling with air (each outer vapor layer), such as collapsible polymer foam, but the latter for penetration at various saturation levels The rate can be easily measured at various thicknesses.
[0335]
For polymer foam materials in particular, it has been found beneficial to test at a high temperature of 31 ° C. so that the in-use conditions for the absorber can be better simulated.
[0336]
In principle, this test is based on Darcy's law, in which the volume flow rate of liquid passing through any porous medium is proportional to the pressure gradient, and the proportionality constant is related to permeability. is doing:
Q / A = (k / η)^*(ΔP / L)
In the formula:
Q = volume flow rate [cm^Three/ S];
A = cross-sectional area [cm²];
k = penetration rate (cm²(1 Darcy is 9.869)^*10^-13m²Equivalent to);
η = viscosity (poise) [Pa^*s];
ΔP / L = pressure gradient [Pa / m];
L = sample caliper [cm]
Thus, the permeability can be calculated by measuring pressure drop and volumetric flow rate through the sample at a constant or predetermined sample cross-sectional area and test fluid viscosity:
k = (Q / A)^*(L / ΔP)^*η
This test relates first to cross-plane permeability (ie, the direction of flow is essentially along the thickness dimension of the material), and second to in-plane permeability (ie, the direction of flow is x of the material). (It is in the y direction) and can be executed by two kinds of correction methods.
[0337]
A test set-up for a simplified cross-plane permeability test can be seen in FIG. 1, which is a partially exploded cross-sectional view, but not a scaled view of the sample cell, as a schematic and inset of the overall apparatus.
[0338]
The test mechanism generally comprises a circular or cylindrical sample cell (120) having an upper portion (121) and a lower portion (122). The spacing between these parts can be measured and can therefore be adjusted by caliper meters (145) and adjusting screws (140) arranged on each of the three outer peripheries. In addition, the device connects several liquid reservoirs (150, 154, 156), including a height adjuster (170) for the water supply reservoir (150), as well as the tube (180), the sample cell and the rest of the device. The quick release fitting (189) and the valves (182, 184, 186, 188). The differential pressure transducer (197) is connected through the tube (180) to the upper pressure detection point (194) and the lower pressure detection point (196). The computer device (190) for controlling the valve is further connected to a differential pressure transducer (197), a temperature probe (192), and a load cell (198) with a weight scale by wiring (199).
[0339]
A circular sample (110) having a diameter of 1 inch is passed by a flexible tube (180), such as a tygon tube, through a water absorption joint (132) to a water supply reservoir (150) and a water discharge joint ( 133) two sheets inside the sample cell (120) made from two 1 inch inner diameter cylindrical parts (121, 122) which are attached to the discharge reservoir (154) through Located between the porous screens (135). A closed cell foam gasket (115) provides protection against leakage around the sides of the sample. The test sample (110) is compressed to a diameter corresponding to the desired wet compression set at 0.2 psi (about 1.4 kPa) unless otherwise specified. The liquid is flowed through the sample (110) to reach a steady state flow. Once steady state flow through the sample (110) is established, volume flow rate and pressure drop are recorded as a function of time using the load cell (198) and differential pressure transducer (197). The experiment can be performed at any pressure up to a pressure head of 80 cm water (about 7.8 kPa), which can be adjusted by the height adjuster (170). From these measurements, the flow rate at various pressures on the sample can be measured.
[0340]
This device is supplied by Porous Materials, Inc., Ithaca, New York under the name PMI Liquid Permeability Meter, as detailed in the 2/97 user manuals. Such a penetrometer is commercially available. This device includes two stainless steel frit as the porous screen (135), also specified in the pamphlet. The apparatus includes a sample cell (120), a water supply reservoir (150), a water discharge reservoir (154), a waste liquid reservoir (156) and valves and fittings for filling and emptying, an electronic balance, and a computer monitoring and valve control device (190).
[0341]
The gasket material (115) is Closed Cell Neoprene Sponge SNC-1 (soft) as supplied by the Netherland Rubber Company, Cincinnati, Ohio. A set of different thicknesses in 1/16 "increments (about 0.159 cm) to cover a thickness in the range of 1/16" to 1/2 "(about 0.159 cm to about 1.27 cm) You have to get the materials.
[0342]
In addition, a supply of compressed air of at least 60 psi (4.1 bar) is required to operate each valve.
[0343]
The test solution is deionized water.
[0344]
The test is then performed by the following steps:
1) Preparation of test sample:
In the preliminary test, it is determined whether one or more test sample layers are required, with the tests outlined below being performed at minimum and maximum pressures. The number of layers is then 0.5 m with a minimum pressure drop^Three/ M and 15m at maximum pressure drop^ThreeAdjust so that the flow rate during the test can be maintained between / sec. The flow rate for the sample must be less than the flow rate for the blank at the same pressure drop. If the sample flow rate exceeds the blank flow rate for a constant pressure drop, more layers must be added to reduce the flow rate.
[0345]
Sample size: Samples are cut to a 1 "(about 2.54 cm) diameter using an arch punch such as that supplied by McMaster-Carr Supply Company, Cleveland, Ohio. If their internal strength and integrity to maintain the structure of the sample during the required operation is too small, conventional low basis weight support means such as PET scrims or nets can be added.
[0346]
Accordingly, at least two samples (each made from the required number of layers if necessary) are pre-cut. One of these is then saturated in deionized water at the temperature at which the experiment is conducted (70 ° F. (31 ° C. unless otherwise specified)).
[0347]
The wet sample caliper has a hold-down diameter of 11.8 "(about 2.86 cm) and applies a pressure of 0.2 psi (about 1.4 kPa) on the sample (110) unless otherwise specifically desired. Measure using a caliper meter (as supplied by AMES, Waltham, Mass., USA) under the desired compression pressure at which the experiment is performed (if necessary after a 30 second stabilization time).
[0348]
Appropriate combinations of gasket materials are selected such that the total thickness of the gas sketching foam (115) is 150-200% of the thickness of the wet sample (various thicknesses to achieve the desired total thickness). Note that some gasket material combinations may be required). The gasket material (115) is cut to a circular size of 3 "diameter and a 1 inch (2.54 cm) hole is drilled in the center using an arch punch.
[0349]
If the sample dimensions change upon wetting, the sample must be cut to obtain the required diameter during the wetting stage. This can also be evaluated in this preliminary test by monitoring each dimension. If these change so that gaps are formed or that the sample forms a fold that prevents the sample from contacting the porous screen or frit smoothly, the cut diameter must be adjusted accordingly. Don't be.
[0350]
The test sample (110) is placed inside the hole in the gasket foam (115) and the composite is placed on top of the lower half of the sample cell so that the sample is in flat and smooth contact with the screen (135). To ensure that no gaps are formed on both sides.
[0351]
The upper part (121) of the test cell is laid flat on a lab bench (or other horizontal plane) and all three caliper meters (145) attached to it are zeroed.
[0352]
The upper part (121) of the test cell is then placed on the lower part (122) so that the gasket material (115) and the test sample (110) lie between the two parts. Thereafter, the upper part and the lower part are tightened by the fixing screw (140) so that the three caliper meters are adjusted to the same value when measured on the wet sample under each of the above pressures.
[0353]
2) To prepare the experiment, start the program on the computer device (190) and enter the sample identification, each pressure etc.
3) Run the test for several pressure cycles with the first pressure being the minimum pressure on one sample (110). The results of individual pressure runs are placed in separate result files by the computer device (190). Data is taken from each of these files for the calculations described below (a separate sample must be used for the next test run of material). 4) Set the inlet liquid reservoir (150) to the required height and start the test on the computer device (190).
5) The sample cell (120) is then placed in the permeability meter device using the quick disconnect fitting (189).
6) Fill sample cell (120) by opening vent valve (188) and lower fill valve (184, 186). Care must be taken to remove bubbles from the system during this step, but this can be accomplished by inverting the sample cell upside down and venting the osmometer through the drain if bubbles are present. .
When the sample cell is filled up to the Tygon tube attached to the top of the chamber (121), air bubbles are removed from this tube into the waste reservoir (156).
7) After carefully removing bubbles, close the lower fill valve (184, 186), fill the upper portion and open the upper fill valve (182) so that all bubbles can be removed more carefully.
8) Fill the liquid reservoir to the full water line (152).
[0354]
The flow through the sample is then started by starting the computer device (190).
[0355]
After the temperature in the sample chamber reaches the required value, the test is ready to begin.
[0356]
When the experiment is initiated by the computer device (190), the outlet flow is automatically diverted from the waste reservoir (156) to the discharge reservoir (154), and the pressure drop and temperature are monitored as a function of time over several minutes. Is done.
[0357]
When the program ends, the computing device provides the recorded data (by number and / or illustration)
If desired, the permeability can be measured with various pressure heads using the same test sample, thereby increasing pressure from run to run.
[0358]
Devices, especially frit, load cells, thermocouples and pressure transducers, must be cleaned every two weeks according to the device supplier's instructions and must be calibrated at least once a week.
[0359]
The differential pressure is recorded by differential pressure transducers connected to pressure probe measurement points (194, 196) on the upper and lower sides of the sample cell. Since there may be other flow resistances in the chamber in addition to the recorded pressure, each experiment must be corrected by a blank test run. Blank test runs must be performed on each day at the required pressure of 10, 20, 30, 40, 50, 60, 70, 80 cm. The penetrometer will output the average test pressure for each experiment and also the average flow rate.
[0360]
For each pressure at which the sample was tested, the flow rate was blank corrected by the computer system (190) correcting the average test pressure (actual pressure) for the pressure difference recorded at each height to produce a further corrected pressure. As recorded. This correction pressure is DP used in the following permeability equation.
[0361]
The permeability can then be calculated at each required pressure and all penetrations must be averaged to determine k for the material being tested.
[0362]
For each sample, three measurements must be taken at each head and the results averaged to calculate the standard deviation. However, the same sample must be used to measure the permeability with each head, but a new sample must then be used to perform the second and third measurements.
[0363]
Measurement of in-plane permeability under the same conditions as the above-mentioned cross-plane permeability is schematically shown in FIGS. 2 (A) and 2 (B), which shows a partially exploded cross-sectional view, but not a proportional scale of the sample cell alone. This can be accomplished by modifying the above device as depicted. Equivalent elements are labeled equally as sample cell (210) in FIG. 2 correlates to number (110) in FIG. Thus, the cross-plane simple sample cell (120) of FIG. 1 allows liquid to flow only in one direction (either in the flow direction or in the front-rear direction, depending on how the sample is placed in the cell). It replaces the simple in-plane sample cell (220) that is designed to do so. Care must be taken to minimize the formation of liquid flutes along the wall (wall effect), as this can inadvertently produce high permeability readings. The subsequent test method is executed in exactly the same way as the cross-plane simple test.
[0364]
Sample cell (220) essentially described sample cell (120) in the cross-plane test described above, except that the filling tube is directed to a water absorption joint (232) at the bottom of cell (220). Is designed to be placed in the device. FIG. 2 (A) shows a partially exploded view of the sample cell, and FIG. 2 (B) shows a cross-sectional view through the sample level.
[0365]
The test cell (220) is made of two pieces: a lower piece (225), such as a rectangular box with a flange, and an upper piece (also fitted with a flange that fits inside the lower piece (225)). 223). The test sample is cut to a size of 2 "inch x 2" inch (about 5.1 cm x 5.1 cm) and placed inside the lower piece. The upper piece (223) of the sample chamber is then placed in the lower piece (225) and rests on the test sample (210). A neoprene rubber seal (224) that cannot be compressed for sealing is attached to the upper piece (223). The test fluid flows from the water supply reservoir through the Tygon tube to the sample space and the water absorption joint (232) and then through the water discharge joint (233) to the water discharge reservoir. In this test embodiment, temperature control of the liquid passing through the sample cell may be inadequate due to the low flow rate, and the sample is thereby pumped through the heating chamber (227) with conditioned water. The desired test temperature is maintained by a heating device (226). The gap in the test cell is set with a caliper that corresponds to the desired wet compression, usually 0.2 psi. Use shims (216) in the size range of 0.1 mm to 20.0 mm, optionally using a combination of several shims to set the correct caliper.
[0366]
At the start of the experiment, the test cell (220) is rotated 90 ° (the sample is vertical) and the test solution is allowed to flow slowly from the bottom. This is necessary to ensure that all air is exhausted from the sample and the water absorption / discharge joint (232/233). The test cell (220) is then rotated back to the initial position so that the sample (210) can be level. The subsequent procedure is the same as that described above for cross-plane permeability, i.e. the feed reservoir is placed at the desired height, the flow is equilibrated, and the flow rate and pressure drop are measured. Permeability is calculated using Darcy's law. This procedure is repeated for higher pressures as well.
[0367]
For samples with very low permeability, it may be necessary to increase the drive pressure, for example by extending the height or applying additional air pressure to the reservoir to obtain a "measurable flow rate" There is a case. The in-plane permeability can be measured independently of the flow direction and the front-rear direction, depending on how the sample is placed in the test cell.
[0368]
<General liquid penetration test>
The general permeability test can measure the permeability as a function of saturation for any porous material. The principle of this test is similar to that of the simple test, the essential difference is that the sample is loaded with a specified amount of air in addition to the liquid load, which causes a certain degree of saturation. This is achieved by the test arrangement schematically depicted in FIG. 3 which defines the principle and general cross-plane permeability, and FIG. 4 which shows the difference in general in-plane permeability. The numbers not indicated correspond to the numbers in FIG. 1 (for example, water reservoir (356) corresponds to water reservoir (156)).
[0369]
In it, the sample cell (320/420) is likewise fixed on the height adjustment device (372) in addition to the water supply reservoir (350) whose height can be adjusted by means (370). (Not shown in FIG. 4). This water supply reservoir limits the first height difference (357) compared to the water discharge reservoir (354), which is related to the differential pressure Δp (which represents the differential pressure for calculating the permeability). . The feed reservoir (350) limits the second height difference (359) to the sample height associated with the differential pressure Δp (c), which is the difference associated with saturation within the sample. Refers to pressure, whereby higher capillary aspiration is typically correlated with lower saturation.
[0370]
The experiment starts with a low ΔPc (close to 0 cm water) where the sample will be 100% saturated. The liquid flows through the sample due to the applied pressure drop Δp (c) (water supply reservoir height-water discharge reservoir height). At steady state, the uptake of liquid in the drainage reservoir is measured as a function of time. Permeability can be calculated from pressure drop and volumetric flow rate data using Darcy's law. The exact saturation can be obtained by comparing the weight of the dry sample before the test and the wet sample after the test.
[0371]
In order to measure permeation at less than 100% saturation, first a new test sample is 100% saturated as described in the paragraph above. The sample is then moved to a higher height (eg 10 cm) and allowed to equilibrate at that height. During this time, liquid continuously flows from the water supply reservoir to the water discharge reservoir. Saturation within the sample will decrease over time. When steady state is reached, i.e., when the uptake vs. time plot is linear, flow rate, pressure drop and saturation are measured as above. This procedure is repeated for several sample heights using the new sample.
[0372]
In order to obtain a measurable flow rate, it may be necessary to increase the pressure drop between the water supply and discharge reservoirs as saturation decreases. This is because for most porous materials, the permeability decreases steeply with decreasing saturation. It is necessary to ensure that the pressure drop between the water supply reservoir and the water discharge reservoir is much smaller than the capillary suction.
[0373]
To ensure that the liquid level does not change significantly while waiting to reach a steady state, it is necessary to use wide mouth liquid reservoirs (352, 354).
[0374]
This test gives the permeability to saturation for the desorption cycle. That is, the sample initially has a higher saturation. Of course, permeability data can be generated for the absorption cycle, but some hysteresis effects may occur and should not be used in this evaluation.
[0375]
A sample cell (320) for a general cross-plane permeability test includes two frit (335) disposed above and below the sample (310), so that a sample for a simple cross-plane permeability test. Essentially different from cell (120). For these frits (335), it is necessary to ensure that most of the resistance to flow is provided by the sample and the frit resistance can be ignored. A finely perforated, thin film above the coarse frit allows measurements up to high heights without providing significant resistance to flow. The frit has a sufficiently high bubble point pressure corresponding to a water height of about 200 cm or more, but must be selected to provide a low flow resistance at the same time. This can be better achieved by selecting a sufficiently thin membrane with the required bubble point pressure covering the more open support structure.
[0376]
For the general permeability test, care must be taken that the air contacts the sample through the sides so that the saturation can be varied depending on Δp (c). Therefore, the design of the sample cell is essentially the same as the test cell for the simple chamfer test except for the following points. That is, the foam gasket material is removed, and an apparatus for adjusting the gap between the upper and lower portions allows samples to be sampled under a desired pressure of 0.2 psi (about 1.4 kPa) unless otherwise required. To maintain (along with the weight of the upper part (321)) it is replaced by a constant pressure generator such as a weight (317).
[0377]
A sample cell (420), which is a design derived from the simple in-plane tests and principles described above, for the general in-plane permeability test is shown in FIG. Thus, liquid flows into the sample cell (420) through a water inlet (432) and a water outlet (433) connected to a membrane (435) such as a frit of the type described above (335 for frit). To do. The test sample (410) is positioned so that its end overlaps the two frits, but not the 2 inch x 2 inch (about 5.1 cm x 5.1 cm) central portion, thereby Wrinkles and gaps between the membrane and the membrane are avoided. The test sample (410) is a sample with a weight (417) used to adjust the pressure at which the experiment is performed (0.2 psi (about 1.4 kPa) unless otherwise desired and specified). Located between the upper and lower portions of the cell (420). Further, the sample is maintained at a constant temperature by the heating device (426), for example by pumping a constant temperature of water through the heating chamber (427).
[0378]
Again for this test mechanism, it is essential that air can flow into the sample through the sides to allow for various degrees of saturation.
[0379]
<Viscosity of liquid>
Liquid viscosity is an important input parameter for the above measurements and must be obtained for each temperature for each liquid, either from well-known tables or formulas, or measured by well-established measurement methods .
[0380]
<Capillary adsorption>
<Purpose>
The purpose of this test is to measure the capillary absorption capacity as a function of height of the storage absorbent member of the present invention. (This test is also based on the capillary as a function of height of a high surface area material, ie a material that does not contain an osmotic absorbent such as a hydrogel-forming absorbent polymer or any other material utilized in the absorbent member. It is also used to measure absorption capacity, but the discussion below will consider the capillary adsorption method as it relates to measuring the total storage absorbent member.) Capillary adsorption is a liquid-absorbing structure. It is a basic property of any absorbent that governs how it is absorbed into it. In capillary adsorption experiments, the capillary adsorption capacity is measured as a function of fluid pressure due to sample height relative to the test fluid reservoir.
[0381]
The method of measuring capillary adsorption is clearly recognized. For a discussion of the method for measuring capillary adsorption of absorptive structures, see Burgeni, AA and Kapur, C., “Capillary Sorption Equilibria in Fiber Masses”, Textile Research Journal, 37 (1967), 356-366; Chatterjee, PK, “Absorbency”, Textile Science and Technology 7, Chapter II, pp29-84, Elsevier Science Publishers BV, 1985; and published on 9 September 1986 by Weisman et al. See U.S. Pat. No. 4,610,678. The disclosure of each of these references is incorporated herein by reference as part of the specification.
[0382]
<Principle>
A porous glass frit is connected to a liquid reservoir on the scale through a continuous column of liquid. Samples are maintained under certain limited weights throughout the experiment. As the porous structure absorbs liquid as needed, the weight loss in the scaled liquid reservoir is recorded as the liquid uptake and adjusted for glass frit uptake as a function of height and evaporation. The uptake or absorption capacity at various capillary suctions (hydrostatic tension or height) is measured. Incremental absorption occurs due to an incremental decrease in frit (ie, a decrease in capillary suction).
[0383]
During the experiment, time is also monitored so that the initial effective uptake rate (g / g / h) at a height of 200 cm can be calculated.
[0384]
<Reagents>
Test solution: Synthetic urine is prepared by completely dissolving the following materials in distilled water.
[0385]

[0386]
<General description of device mechanism>
In FIG. 2A used for this test, the capillary adsorption test apparatus, generally designated as 520, is operated under TAPPI conditions (50% RH, 25 ° C.). The test sample is connected to a scaled liquid reservoir labeled 506 containing the test solution through a continuous column of test solution (synthetic urine) on a glass frit, shown as 502 in FIG. 2 (A). Placed on. This reservoir 506 is placed on a scale 507 connected to a computer (not shown). Scales must be able to read up to 0.001 g; such scales are available as PR1203 from Mettler Toledo (Heightstown, NJ). The glass frit 502 is placed on a vertical slide, generally indicated as 501 in FIG. 2A, to allow vertical movement of the test sample to expose the test sample to various suction heights. The vertical slide may be a rodless drive attached to the computer to record the suction height and corresponding time to measure the amount of liquid uptake by the test sample. A preferred rodless actuator is an industrial product 202X4X34N-1D4B-84-PCSE, which can be powered by an electric device ZETA 6104-83-135 available from CompuMotor (Rohnert, Calif.). Available from Industrial Devices (Novato, CA). When data is measured and data is sent from the drive unit 501 and the scale 507, capillary adsorption / absorption capacity data is easily generated for each test sample. Similarly, the vertical movement of the glass frit 502 can be controlled by connecting a computer to the driving device 501. For example, the drive can command the glass frit 502 to move vertically only after reaching “equilibrium” (defined below) at each suction height.
[0387]
The lower part of the glass frit 502 is connected to a Tygon® tube that connects the frit 505 to a drain three-way stopcock 509. The drain cock 509 is connected to the liquid reservoir 505 by a glass tube 504 and a cock 510. (The stopcock 509 is opened toward the drain only during cleaning of the apparatus or during the removal of bubbles.) The glass tube 511 connects the liquid reservoir 505 and the liquid reservoir 506 with a scale by the stopcock 510. The liquid reservoir 506 with a scale is composed of a lightweight 12 cm diameter glass dish 506A and a cover 506B. Cover 506B has a hole through which glass tube 511 contacts the liquid in reservoir 506. The glass tube 511 must not contact the cover 506B, otherwise unstable scale readings will occur and test sample measurements will not be available.
[0388]
The diameter of the glass frit must be sufficient to fit the piston and cylinder device described below to hold the test sample. The glass frit 502 must be fitted with a jacket so that a constant temperature control from the heating bath is possible. The frit is a 350 ml fritted glass circular funnel defined as having 4 to 5.5 μm pores available from Corning Glass Co. (Corning, NY) as # 36060-350F. The pores are fine enough to keep the frit surface wet at a defined capillary suction height (the glass frit does not allow air to enter the continuous column of test fluid below the glass frit ).
[0389]
As described above, the frit 502 is connected to the liquid reservoir 505 or the liquid reservoir 506 with a scale by a tube depending on the position of the three-way cock 510.
[0390]
Glass frit 502 is jacketed to accept water from a constant temperature bath. This will ensure that the glass frit temperature is maintained at a constant temperature of 88 ° F. (31 ° C.) during the test procedure. As shown in FIG. 2 (A), the glass frit 502 is provided with a water intake port 502A and a water discharge port 502B, which form a closed loop with a circulating heating bath, generally designated 508. (A glass jacket is not depicted in FIG. 2 (A). However, water introduced from the bath 508 to the jacketed glass frit 502 does not contact the test solution, and the test solution is a constant temperature bath. (The water in the isothermal bath circulates through the jacket wall of the glass frit 502.)
Reservoir 506 and scale 507 are housed in a box to minimize evaporation of test fluid from the scaled reservoir and to enhance the stability of the scale during the course of the experiment. This box, generally designated 512, has a top and a wall with a hole through which the tube 511 is inserted.
[0390]
The glass frit 502 is shown in more detail in FIG. FIG. 2B is a cross-sectional view of the glass frit in which the water absorption port 502A and the water discharge port 502B are not shown. As mentioned above, the glass frit is a 350 ml fritted glass circular funnel with defined 4-5.5 μm pores. Referring to FIG. 2B, the glass frit 502 comprises a cylindrical jacketed funnel designated 550 and a glass frit disk designated as 560. The glass frit 502 further confines the test sample, shown as 570, and further provides a small sealing pressure to the test sample, generally a cylinder / piston set shown as 565 (comprising a cylinder 566 and a piston 568). It has a solid. To prevent excessive evaporation of the test fluid from the glass frit disk 560, a Teflon ring, designated 562, is placed on top of the glass frit disk 560. The Teflon® ring 562 is 0.0127 cm thick (available as a seat stock from McMasterCarr as # 8569K16 and cut to the appropriate size), and the frit outside the cylinder 566 Used to coat the disk surface, thus minimizing evaporation from the glass frit. The outer diameter and inner diameter of the ring are 7.6 and 6.3 cm, respectively. The inner diameter of the Teflon® ring 562 is approximately 2 mm smaller than the outer diameter of the cylinder 566. The Viton® O-ring (available from McMasterCarr as # AS568A-150 and AS568A-151) 564 is more useful in preventing evaporation and the inner wall of the cylindrical jacketed funnel 550 and the Teflon Placed on top of the Teflon® ring 562 to seal the gap between the ® ring 562. If the O-ring outer diameter is larger than the inner diameter of the cylindrical jacketed funnel 550, the O-ring diameter is reduced to fit the funnel as follows: the O-ring is cut open and the required amount of O-ring material And the O-ring is reattached so that it contacts the inner wall of the cylindrical jacketed funnel 550 over its entire circumference.
[0392]
As described above, the cylinder / piston assembly, generally shown in FIG. 2B as 565, encloses the test sample and provides a small sealing pressure to the test sample 570. Referring to FIG. 2 (C), the assembly 565 includes a cup-like Teflon.RTM. Piston designated as cylinders 566, 568 and one or more weights (if necessary) that fit the inner piston 568. (Not shown). (Optional weights will be used if necessary to adjust the combined weight of the piston and any weights so that a 0.2 psi sealing pressure is achieved depending on the dry diameter of the test sample. This is described below.) Cylinder 566 is a Lexan® bar stock and has the following dimensions: 7.0 cm outer diameter, 6.0 cm inner diameter and 6.0 cm height. The Teflon® piston 568 has the following dimensions: an outer diameter that is 0.02 cm smaller than the inner diameter of the cylinder 566. As shown in FIG. 2D, the end of the piston 568 that does not contact the test sample has any weight necessary to achieve a test sample sealing pressure of 0.2 psi (1.4 kpa) (test Is perforated to provide a chamber 590 that is 5.0 cm diameter x about 1.8 cm deep. In other words, the total weight of the piston 568 and any optional weight (not shown) divided by the actual diameter of the test sample (when dry) will achieve a sealing pressure of 0.2 psi. Must. Cylinder 566 and piston 568 (and any weight) are allowed to equilibrate at 31 ° C. for at least 30 minutes before performing capillary adsorption capacity measurements.
[0393]
During capillary adsorption experiments, non-surfactant treated or mixed spun perforated film (14 cm × 14 cm) is used to cover the glass frit 502 to minimize air destabilization around the sample. The perforations are large enough to prevent condensation from occurring on the lower surface of the film during the experiment.
[0394]
<Preparation of test sample>
The test sample can be obtained by punching out a 5.4 cm diameter circular structure from the storage absorbent member. If the member is an absorbent component, other components of the product must be removed prior to testing. The member cannot be separated from other components of the product without significantly changing its structure (eg, density, relative placement of component materials, physical properties of the constituent materials, etc.) or the member is an absorbent component In the absence of the test sample, the test sample is prepared by combining all the materials comprising the member so that the combination is representative of the member in question. The test sample is a circle with a diameter of 5.4 cm and is cut using an arch punch.
[0395]
The dry weight of the test sample (used below to calculate the capillary adsorption capacity) is the weight of the test sample prepared under ambient conditions as described above.
[0396]
<Experiment setup>
1. Place a clean, dry glass frit 502 on a funnel holder attached to a vertical slide 501. Move the vertical slide funnel holder so that the glass frit is at a height of 0 cm.
[0397]
2. As described above, the components of the device are installed as shown in FIG.
[0398]
3. Place a scaled liquid reservoir 506 with a 12 cm diameter on the scale 507. A plastic lid 506B is placed over the scaled liquid reservoir 506, and the balance box 512 is covered with a plastic lid, each of which has a small hole to allow the glass tube 511 to fit therethrough. The glass tube must not be in contact with the scaled liquid reservoir lid 506B, otherwise an unstable scale reading will occur and the measured value will not be usable.
[0399]
4). The stopcock 510 is closed toward the tube 504 and opened toward the glass tube 511. The liquid reservoir 505 previously filled with the test liquid is opened so that the test liquid can flow into the tube 511 to fill the liquid reservoir 506 with the scale.
[0400]
5). The glass frit 502 is leveled and fixed in place. Similarly, it ensures that the glass frit is dry.
[0401]
6). A Tygon (registered trademark) tube 503 is attached to the stopcock 509. (The tube must be long enough to reach the glass frit 502 at the highest point of 200 cm without a kink.) Fill the Tygon® tube with test fluid from the liquid reservoir 505.
[0402]
7. A Tygon® tube 503 is attached to the horizontal glass frit 502 and then the stopcock 509 and stopcock 510 leading from the liquid reservoir 505 to the glass frit 502 are opened. (The stopcock 510 must be closed with respect to the glass tube 511.) Fill the glass frit 502 with the test solution and remove any air trapped during the filling of the horizontal glass frit. Continue filling until the liquid level exceeds the top of the glass frit disk 560. Empty the funnel and remove any air bubbles inside the tube and funnel. The bubbles can be removed by inverting the glass frit 502 and allowing the bubbles to stand out through the drain of the stopcock 509. (Air bubbles typically collect on the bottom of the glass frit disk 560.) With a sufficiently small level that will fit inside the jacketed funnel 550 and on the surface of the glass frit disk 560. Level the frit again.
[0403]
8). The glass frit is zeroed using a scaled liquid reservoir 506. Take one Tygon® tube long enough to do this and fill it with the test solution. One end is placed in a scaled liquid reservoir 506 and the other end is used to place the glass frit 502. The level of test fluid indicated by the tube (equivalent to the level of the scaled fluid reservoir) is 10 mm below the top of the glass frit disk 560. If this does not fit the situation, adjust the amount of liquid in the reservoir or reset the zero position on the vertical slide 501.
[0404]
9. The water discharge port and water absorption port from the constant temperature bath 508 are attached to the glass frit water absorption port and water discharge ports 502A and 502B, respectively, by means of tubes. The temperature of the glass frit disk 560 is brought to 31 ° C. This can be measured in part by filling a glass frit with a test solution and measuring the temperature after it has reached an equilibrium temperature. In order to allow heat dissipation during the transfer of water from the bath to the glass frit, the bath would need to be set at a temperature somewhat above 31 ° C.
[0405]
10. Allow the glass frit to equilibrate for 30 minutes.
[0406]
<Capillary adsorption parameters>
The following describes a computer program that measures how long a glass frit stays at each height.
[0407]
In the capillary adsorption test software program, the test sample is at a certain height from the liquid reservoir. As described above, the liquid reservoir is placed on the scale so that the computer can read the scale at the end of a known time interval and calculate the flow rate (delta reading / time interval) between the test sample and the reservoir. is there. For the purposes of this method, a test sample is considered to be in equilibrium when the flow rate is less than the specified flow rate for a specified number of consecutive time intervals. It is recognized that for certain materials, the equilibrium may not actually be reached when the specified “equilibrium constant” is reached. The time interval between readings is 5 seconds.
[0408]
The number of readings in the delta table is defined as “equilibrium sample” in the capillary adsorption menu. The maximum number of deltas is 500. The flow rate constant is defined as “equilibrium constant” in the capillary adsorption menu.
[0409]
The equilibrium constant is input in units of g / sec within the range of 0.0001 to 100,000.
[0410]
The following is a simplified example of logic. The table shows the scale reading and the delta flow calculated for each time interval.
[0411]
Equilibrium sample = 3
Equilibrium constant =. 0015
[Table 1]

[0412]
[Table 2]

[0413]
[Table 3]

[0414]
The equilibrium uptake for the simplified example above is 0.318 g.
[0415]
The following is the C code used to determine the equilibrium uptake:
[Table 4]

[0416]
<Capillary adsorption parameters>
Load description (sealing pressure): 0.2 psi load
Equilibrium sample (n): 50
Equilibrium constant: 0.0005 g / sec
Setup height value: 100cm
Final height value: 0cm
Hydrostatic head parameters: 200, 180, 160, 140, 120, 100, 90, 80, 70, 60, 50, 45, 40, 35, 30, 25, 20, 15, 10, 5, and 0 cm
The capillary adsorption test procedure is performed using the full height specified above in the above order for the measurement of the capillary adsorption capacity. Even if it is desirable to measure capillary adsorption capacity at a specific height (eg, 35 cm), the entire series of hydrostatic water head parameters must be completed in a defined sequence. All these heights are used during the performance of the capillary adsorption test to create a capillary adsorption isotherm for the test sample, but the present disclosure discloses specific heights of 200, 140, 100, 50, 35 and 0 cm. The storage absorbent members will now be described with respect to their absorption characteristics.
[0417]
<Capillary adsorption test procedure>
1) Follow the experimental setup procedure.
2) Verify that the constant temperature bath 508 is switched on and water is circulating through the glass frit 502 and that the temperature of the glass frit disc 560 is 31 ° C.
3) Place the glass frit 502 at a suction height of 200 cm. The stopcocks 509 and 510 are opened to connect the glass frit 502 to the scaled liquid reservoir 506 (the stopcock 510 is closed to the liquid reservoir 505). The glass frit 502 is allowed to equilibrate for 30 minutes.
4) Input the above capillary adsorption parameters into the computer.
5) Close the stopcocks 509 and 510.
6) Move the glass frit 502 to a setup height of 100 cm.
7) Place the Teflon® ring 562 on the surface of the glass frit disk 560. Place O-ring 564 on the Teflon ring. A preheated cylinder 566 is placed concentrically on the Teflon® ring. Test sample 570 is placed concentrically in cylinder 566 on glass frit disk 560. Piston 568 is placed in cylinder 566. If necessary, an additional limiting weight is placed in the piston chamber 590.
8) Cover glass frit 502 with perforated film.
9) The figure reading at this point is zero or the tare reading is fixed.
10) Move the glass frit 502 to 200 cm.
11) Open stopcocks 509 and 510 (stopcock 510 is closed to liquid reservoir 505) and begin reading scale and time.
[0418]
<Glass frit correction (Blank correction loading)>
Since the glass frit disk 560 is a porous structure, the glass frit (502) capillary adsorption uptake (blank corrected uptake) is measured and reduced to obtain the true test sample capillary adsorption uptake. There must be. Glass frit correction is performed for each new glass frit used. To obtain the blank uptake (g), the capillary adsorption test procedure is performed as described above except that no test sample is used. The elapsed time at each specified height is equal to the blank time (s).
[0419]
<Correction of evaporation loss>
1) Move the glass frit 502 upwards 2 cm of zero and at that height open the stopcocks 509 and 510 (close to reservoir 505) and allow to equilibrate for 30 minutes.
2) Close the stopcocks 509 and 510.
3) Place the Teflon® ring 562 on the surface of the glass frit disk 560. Place O-ring 564 on the Teflon ring. A preheated cylinder 566 is placed concentrically on the Teflon® ring. Piston 568 is placed in cylinder 566. Place the perforated film on the glass frit 502.
4) Open stopcocks 509 and 510 (close to reservoir 505) and record scale reading and time over 3.5 hours. Calculate sample evaporation (g / hr) as follows:
[Scale reading after 1 hour-Scale reading after 3.5 hours] /2.5 hours
Even after all of the above cautions are observed, typically about 0.10 g / hr will occur for some evaporation loss, both test sample and frit correction. Ideally, sample evaporation is measured for each newly installed glass frit 502.
[0420]
<Washing the device>
When the glass frit 502 is newly installed, a new Tygon (registered trademark) tube 503 is used. Glass tubes 504 and 511, liquid reserve 505, and scaled liquid reservoir 506 are washed with 50% Clorox Bleach® in distilled water if bacterial contamination is visible, then rinsed with distilled water To do.
[0421]
a. Cleaning after each experiment
At the end of each experiment (after the test sample is removed), the glass frit is flushed forward with 250 ml test liquid from the liquid reservoir 505 to remove residual test sample from the holes in the glass frit disk. (Ie, the test solution is introduced into the bottom of the glass frit). Stopcocks 509 and 510 are open to liquid reservoir 505, closed to scaled liquid reservoir 506, the glass frit is removed from its support, and rinsed first with the test solution upside down, then Rinse with acetone and test solution (synthetic urine). During rinsing, the glass frit must be placed upside down and the rinsing liquid is spouted onto the test sample contact surface of the glass frit disc. After rinsing, the glass frit is flushed a second time forward with 250 ml test solution (synthetic urine). Finally, the glass frit is reattached to the support and the frit surface is leveled.
[0422]
b. Glass frit performance monitoring
The performance of the glass frit must be monitored using a glass frit setup at the 0 cm position after each cleaning procedure and each new installation of each glass frit. Inject 50 ml of test fluid onto a leveled glass frit disk surface (without Teflon® ring, O-ring and cylinder / piston components). Record the time required for the test solution level to drop 5 mm above the glass frit disk surface. If this time exceeds 4.5 minutes, regular cleaning must be performed.
[0423]
c. Regular cleaning
Periodically (see frit performance monitoring section above), glass frit is thoroughly cleaned to prevent clogging. The rinse solution is distilled water, acetone, 50% Clorox Bleach® (to remove bacterial growth) dissolved in distilled water and a test solution. Cleaning includes removing the glass frit from the support and disconnecting all tubes. The glass frit is flushed forward (ie, the test solution is introduced at the bottom of the glass frit) with the appropriate liquid and amount in the following order, with the frit upside down:
1. 250ml distilled water
2. 100 ml of acetone
3. 250 ml distilled water
4. 100 ml of 50:50 Clorox® / distilled aqueous solution
5. 250ml distilled water
6. 250 ml of test solution
The cleaning procedure is satisfactory if the performance of the glass frit is within the set flow standard (see above) and no residue can be observed on the glass frit disk surface. If cleaning cannot be performed successfully, the frit must be changed.
[0424]
<Calculation>
The computer is set up to provide a report consisting of the capillary suction height in cm at each defined height, the amount of uptake in time and g. From this data, the capillary suction absorption capacity corrected for both frit uptake and evaporation loss can be calculated. Similarly, the capillary absorption efficiency can be calculated at a specified height based on the capillary suction absorption capacity at 0 cm. In addition, the initial effective uptake rate at 200 cm is calculated.
[0425]
Blank correction capture amount:
Blank correction loading (g)
= Blank uptake (g)-Blank time * Sample evaporation (g / hr) / 3,600 (s / hr)
Capillary suction adsorption capacity (“CSAC”):
CSAC (g / g)
= {Sample uptake (g)-(Sample time * Sample evaporation (g / hr) / 3,600 (s / hr))-Blank corrected uptake (g)} / Dry weight of sample (g)
Initial effective uptake at 200 cm (“IEUR”):
IEUR (g / g / hr) = Sample time (s) at CSAC (g / g) / 200 cm at 200 cm.
[0426]
<Report>
To calculate the Capillary Adsorption Capacity (CSAC) for a given absorbent member or a given high surface area material, a minimum of two measurements must be obtained for each sample and the uptake must be averaged for each height. .
[0427]
Using these data, each number can be calculated:
-Capillary adsorption desorption height (CSDHx) at which material expressed in -cm released x% of its capacity at 0 cm (ie CSAC0);
Capillary adsorption absorption height (CSAHy) in which the material represented by -cm released y% of its capacity at 0 cm (ie CSAC0);
-Capillary adsorption capacity (CSACz) at constant height z expressed in units g {liquid} / g {material}, especially at zero height (CSAC0) and 35 cm, 40 cm and other heights ;
-Capillary adsorption and absorption efficiency (CSAEz) at a constant height z expressed in%, which is the ratio of numerical values to CSAC0 and CSACz.
[0428]
If two materials are combined (a first material as used for collection / distribution material and a second material used as liquid storage material), the CSAC value of the second material (and thus each CSAE value) ) Can be measured from the CSDHx value of the first material.
[0429]
<Teabag centrifugal capacity test (TCC test)>
The TCC test has been developed especially for superabsorbent materials, but it can be easily applied to other absorbent materials.
[0430]
The tea bag centrifuge capacity test measures a tea bag centrifuge capacity value, which is a measure of liquid retention in the absorbent material.
[0431]
The absorbent material is placed in a “tea bag”, soaked in a 0.9 wt% sodium chloride solution for 20 minutes, and then centrifuged for 3 minutes. The ratio of the amount of liquid retained to the initial weight of the dry material is the absorbent capacity of the absorbent material.
[0432]
Pour 2 liters of 0.9 wt% sodium chloride in distilled water into a tray having dimensions of 24 cm × 30 cm × 5 cm. The liquid fill height should be about 3 cm.
[0433]
The tea bag pouch has a size of 6.5 cm × 6.5 cm and is available from Teekanne, Dusseldorf, Germany. The pouch can be heat sealed using a standard kitchen plastic bag sealer (eg, VACUPACK2 PLUS from Krups, Germany).
[0434]
The tea bag is opened by partially carefully cutting and then weighed. Approximately 0.200 g sample of absorbent material accurately weighed to +/− 0.005 g is placed in a tea bag. The tea bag is then sealed using a heat sealer. This is called a sample tea bag. Seal the empty tea bag and use it as a blank.
[0435]
The sample tea bag and blank tea bag are then placed on the surface of the saline solution and soaked for about 5 seconds with a spatula to completely wet (the tea bag will float on the surface of the saline solution, Then completely wet). Start the timer immediately.
[0436]
After a 20 minute soak time, the sample tea bag and blank tea bag are removed from the saline solution and Bauknecht WS130, Bosch 772 NZK096 or equivalent centrifuge so that each bag sticks to the outer wall of the centrifuge basket. Place on the machine (230mm diameter). Close the centrifuge lid, start the centrifuge and increase the speed rapidly to 1,400 rpm. When the centrifuge is stable at 1,400 rpm, start the timer. After 3 minutes, stop the centrifuge.
[0437]
Remove sample and blank tea bags and weigh individually.
[0438]
The tea bag centrifuge capacity (TCC) for a sample of absorbent material is calculated as follows:
TCC = [(weight of sample / tea bang after centrifugation) − (weight of blank / tea bang after centrifugation) − (weight of absorbent material when dried)] ÷ (weight of absorbent material when dried)
In addition, a structure such as a “section” cutout or a specific part of the total absorber can also be measured (ie in that case as viewed as part of the structure or the entire product), for which cutting is performed on the longitudinal axis of the product Over the full width of the product at the measured points. In particular, the “crotch region capacity” can be measured by the definition of the “crotch region” as described above. Other cutouts can be used to measure the “basic volume” (ie, the volume contained in a unit area of a specific area of the product). Depending on the size of the unit area (preferably 2 cm × 2 cm), it will be determined how much averaging will take place-of course, the smaller the size, the less averaging will occur.
[0439]
<Final storage capacity>
A number of methods have been proposed to measure or evaluate the final design storage capacity of the absorber.
[0440]
In the context of the present invention, it is assumed that the final storage capacity of the product is the sum of the final absorption capacity of the individual elements or materials. Various well-established methods can be applied to these individual components as long as they are applied consistently throughout the comparison. For example, a well-established tea bag centrifuge capacity test developed for superabsorbent polymers (SAP) can be used for other materials as well as such SAP materials (see above).
[0441]
Once the capacity for an individual material is known, the total product volume can be calculated by multiplying these numbers (ml / g) by the weight of the material used in the product.
[0442]
For materials with dedicated functionality other than final storage of liquids (such as collection layers etc.), do these materials actually have very little capacity compared to dedicated final liquid storage materials? Or such materials are not intended to be loaded with liquids, so the final storage capacity is negligible so that they must be released to other final storage materials.
[0443]
<Density / Caliper / Basis weight measurement>
For example, a test piece of limited area cut with a sample cutter is weighed to an accuracy of at least 0.1%. The caliper is measured for a test area of 50 mm diameter under an applied pressure of 550 pa (0.08 psi). g / m²The basis weight as the weight per unit area represented by: caliper expressed in mm under a pressure of 550 Pa, and g / cm^ThreeThe density represented by can be easily calculated.
[Brief description of the drawings]
FIG. 1 illustrates various implementations of a permeability test setup. FIG. 1 relates to a simple test for measuring cross-plane permeability.
FIG. 2 illustrates various implementations of a permeability test setup. FIG. 2 relates to a simple test of in-plane permeability.
FIG. 3 illustrates various implementations of a permeability test setup. FIG. 3 relates to a general test for measuring cross-plane permeability.
FIG. 4 illustrates various implementations of a permeability test setup. FIG. 4 relates to a general test for measuring in-plane permeability.
FIG. 5 shows a capillary adsorption test stand (capsorption).
FIG. 6 shows a capillary adsorption test stand (capsorption).
FIG. 7 shows a capillary adsorption test stand (capsorption).
FIG. 8 shows a capillary adsorption test stand (capsorption).
FIG. 9 shows a diaper as an example of an absorber.

Claims (35)

It has a Capillary Sorption Absorption Height (CSAH50) at 50% of its capacity at 0 cm, and further has a permeability k (100) at 100% saturation and further penetration at 50% saturation. An absorbent body comprising a fluid distribution member having a rate k (50) and further comprising a first fluid storage member in liquid communication with the fluid distribution member, wherein the first fluid storage member is at 0 cm It has a Capillary Sorption Absorption Height (CSAH50) of 50% of its capacity, and the fluid distribution member has a number average cell size of 20 μm to 60 μm, a number average hole size of 5 μm to 15 μm, Comprising an open cellular foam having a capillary suction specific surface area of 0.03 m ² / ml to 0.10 m ² / ml, a dry density of 8 mg / cm ^{3 to} 77 mg / cm ³ , 50% saturation of the fluid distribution member The penetration rate k (50) at k is (1 0) that is 14% or more, and CSAH50 of the first fluid storage member absorber being higher than CSAH50 of the fluid distribution member.   The absorber according to claim 1, wherein the first fluid storage member has a CSAH50 of 15 cm or more.   The absorbent body according to claim 2, wherein the first fluid storage member has a CSAH50 of 23 cm or more.   The absorbent body according to claim 3, wherein the first fluid storage member has a CSAH50 of 27 cm or more.   The absorbent body according to claim 4, wherein the first fluid storage member has a CSAH 50 of 30 cm or more.   The absorbent body according to claim 5, wherein the first fluid storage member has a CSAH50 of 47 cm or more.   The absorber according to claim 1, wherein the fluid distribution member has a k (50) value of 18% or more of k (100).   The absorber according to claim 7, wherein the fluid distribution member has a k (50) value of 25% or more of k (100).   The absorber according to claim 8, wherein the fluid distribution member has a k (50) value of 35% or more of k (100).   2. Absorbent according to claim 1, wherein the fluid distribution member has a permeability k (30) at 30% saturation of 3% or more of its k (100).   The absorber according to claim 10, wherein the fluid distribution member has a k (30) value of 5% or more of k (100).   The absorbent body according to claim 1, wherein the fluid distribution member has a CSDH50 value of less than 150 cm.   13. Absorbent body according to claim 12, wherein the fluid distribution member has a CSDH50 value of less than 100 cm.   14. Absorbent body according to claim 13, wherein the fluid distribution member has a CSDH50 value of less than 75 cm.   15. Absorbent body according to claim 14, wherein the fluid distribution member has a CSDH50 value of less than 50 cm.   The absorber according to any one of claims 1 to 15, which expands when the fluid distribution member is wet.   The absorber according to any one of claims 1 to 15, wherein the fluid distribution member collapses again when the liquid is discharged.   18. Absorber according to any one of the preceding claims, further comprising an open cell hydrophilic and flexible polymer foam structure in which the first fluid storage member is in communication with each other. .   The absorbent body according to claim 18, wherein the first fluid storage member expands when wet.   The absorbent body according to claim 19, wherein the first fluid storage member collapses again when the liquid is discharged.   21. Absorbent according to claim 20, wherein the hydrophilic and flexible polymer foam has a capillary collapse pressure as defined herein of at least 15 cm.   20. The absorbent body according to any one of the preceding claims, further comprising a second liquid storage area, whereby both liquid storage areas are in liquid communication with the fluid distribution member.   23. An absorbent body according to claim 22, wherein at least one of said liquid storage areas exhibits a capillary adsorption absorption height (CSAH50) of at least 40 cm at 50% of its maximum capacity.   24. The method of any one of claims 1 to 23, further comprising a crotch region and one or more torso regions, whereby the crotch region has a lower final liquid storage capacity than the combined one or more torso regions. Absorber.   25. The absorbent body of claim 24, wherein the crotch region has a final fluid storage base volume that is less than 0.9 times the average final fluid storage base volume of the absorbent core.   26. The absorbent body of claim 25, wherein the crotch region has a final fluid storage base volume that is less than 0.5 times the average final fluid storage base volume of the absorbent core.   27. The absorbent body of claim 26, wherein the crotch region has a final fluid storage base volume that is less than 0.3 times the average final fluid storage base volume of the absorbent core.   25. The absorbent body of claim 24, wherein the crotch region has a segmented final fluid storage capacity that is less than 49% of the total core final fluid storage capacity.   30. The absorbent body of claim 28, wherein the crotch region has a segmented final fluid storage capacity that is less than 41% of the total core final fluid storage capacity.   30. The absorbent body of claim 29, wherein the crotch region has a segmented final fluid storage capacity of less than 23% of the total core final fluid storage capacity.   31. Absorbent according to any one of claims 24 to 30, further characterized in that at least 50% of the area of the crotch region is essentially free of final storage capacity.   32. The method of claim 24, wherein less than 50% of the final storage capacity is located forward from the crotch zone in the front half of the product and more than 50% of the final storage capacity is located in the back half of the product. The absorber of any one of Claims. 33. The absorbent body of claim 32 , wherein less than 33% of the final storage capacity is located forward from the crotch zone in the front half of the product, and 67% or more of the final storage capacity is located in the back half of the product.   34. Absorbent according to any one of claims 1 to 33, characterized in that it comprises a final liquid storage material that provides at least 80% of the total final storage capacity of the absorbent core.   32. The absorbent body of claim 31 further comprising a final liquid storage material that provides at least 90% of the total final storage capacity of the absorbent core.

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